First: is there a reason not to "always run"? Like it drain food faster?

Second: arriving in the starter village I though: woop, an entire field of crop, regrows every 2 days. So I'll have all the food I need for a looong journey. But my reserve does not incrise. And while in town seems no decrease either.
Is there a "maximum food level" somewhere? Do I need a skill to expand that? What is going on?

The consumption of food is a function of time. Walking, travelling between areas and resting will spend food, even more so if you're traversing harsh terrain (e.g. snow or desert). Running is a convenience and does not factor in the equation. It's best to run everywhere as walking is really slow. Walking has its uses, though, when you are investigating dungeons carefully for traps or trying not to step on certain spots etc.

Regarding wheat, there are two uses for it: 1) sell it to the old man just next to the field, and 2) combine a stack of wheat (40 units) into one unit of food. The latter is done via the herbalism interface (the leaf icon on the bottom right. So the food is actually not all that plentiful considering you have to wait for two days for the what to regrow. The price of food does not rise linearly so you shouldn't buy food for more than three days; later it will be very easy to visit any vendor via portals.

It's good to see that people are still playing this game. Here's one tip: at each level-up, invest one stat point into Speed for every character. Do so every time you level up. Otherwise combat will become nearly impossible later on.

It's realy bothersome this gamealso lacks manual,and even proper fan-collected informations.

I'm far from gaining my first level unfortunately, but here are some things I found:
- seems inside town food supply does not lower.
- ye, those plants don't directly go into food reserve, but into the backpack as herbs. I assume, you can just walk around until they regrow, collect the money for them, and pay the soldiers there when they again ask for taxes.And collect them as food when needed. Of course thereare those twofood-trees nearby too.

My party will be this:
thief, bard, cleric at the back.
barbarian, explorer, soldier at front.
The thief will have: shurriken (meh, I hate consumables), lockpick, disarm trap / learning / bow, quick strike.
The bard will have: merchantilism, perception / learning / song of victory. Spare points go to bow.
The explorer will have: knowledge of terrain and herbs / learning / envenom strike. Spare points go to swords.
The barbarian will have: learning / rage. Spare points go to Sword and Armor.
The soldier will have: powerful strike / learning. Spare points go to Sword and Armor.
The cleric (should realy be called medic, being the healer, not the humbug class) will have its own skills, no need to look at other classes. Will use polearms.
This set seems to cover all needs except instant hit magic (read some stuff about hitting wasps is hard or something), and on paper seems to function from start to finish.

You've made some strong build choices. The main thing to remember is that late game is not about raw damage dealt, but rather stacked damage over time (DoT). That's why each character should deal one type of DoT: for Gaulen I developed the axe skill + envenom. My Paladin specialised in weakness. My thief used sharp weapons and shurikens for bleeding. And my mage would often deal fire damage. Then I had something for every type of enemy.

Herbalism is very important for skill potions. Don't avoid shurikens. They may be rare, but they're cheap and deal ridiculous amounds of bleed damage when scaled at later levels. Buy them wherever you can, then save them for boss battles to win easily.

Oh, and after a couple of levels, you can defeat those guards that extort you for tax money – it has no repercussions on your reputation, and IIRC the townspeople even give you a reward.

That's a nice setup. I run a similar setup in my current run, except my cleric is on the front line and I have a mage instead of a soldier and I swapped thief and explorer

Shurikens are great for tough encounters because of their bleed at higher skill levels.
Herbalism does not affect potions but the amount of herbs you get when you gather them. As a general rule, I won't pick up any herbs until I've maxed this skill.
Don't forget to give your Bard ranks in song of stunning.
Always improve speed when you level up. In my current run, I've also boosted Endurance a lot at early levels and I can recommend doing the same. (You will thank me when archers start hitting your back row and you won't have to pray every time for them not to hit the same guy twice)

Another piece of important advice for beginners: Don't burn all your cash on training. Get some decent gear first. All your front liners should have as much armor as you can find/buy. This will make a huge difference in early fights.

Unfortunately, a lot of skills don't scale well at all. Either consult a spreadsheet or prepare to restart games. Most classes have at least one skill worth investing in long-term within the first 10 levels or so.

In the early game, a lot of units will get one-shot for the first few levels, even though they can become reasonably tanky after a few levels with enough investment.

Gaulen is skillpoint hungry... needs to be tanky and Envenom Weapon is a great point sink, but he also needs to collect herbs and spend a lot of points on food conservation.... ugh.

------------

Two classes seem sort of mandatory...

Playing without a Thief is annoying. Unfortunately, the Thief is mostly a Shuriken-bot, and is otherwise a potato in combat. Can go in front-outside rank with a sword, but max Shuriken and keep the trap and door skills reasonably high. Gaulen can do it at twice the cost, and he already sinks a lot of points into Herbalism and whatnot, yikes. Shurikens do a lot of bleeding damage when you need it.

Cleric doesn't get that many useful skills for a long time, but from what I hear, late-game this class does lots of 2x damage to end-game units, and has a powerful full-party armor buff. Also self-restores HP and Power in combat. Could go on front line to make use of the heal, if the rest of your lineup supports it, but the first few levels can be especially rough. Early heal skills aren't worth points, unfortunately, meaning you don't even have good combat heals for much of the game.

-------------

Everything else is optional and has use cases.

Summoner has the best early-game healing and scales well throughout the game. Can easily max out two summons, but won't have a ton of points to spare. Nalaet for heals and Valvet for DoT stacking works for me. Golot can farm you extra money, but it's very hard to fit the points in and you will not be able to keep three at max level. Some of the others might work too, but burn DoT stacks with some other class damage options.

Barbarian and Soldier are largely interchangeable, but Barbarian will be slightly more oriented toward trash mobs, as it does have Power skills to use tactically. These are the tankiest two units as well, so it's hard not to get at least one of them, though Paladin almost does as well - they can self-heal, but don't have quite as large a health pool.

Wizard has some skills that scale well, and others that don't. Flames is the first good skill, and it stacks burning damage. You could put this unit on Perception duty if you're careful with skillpoints.

Arcane Soldier seems bad, but Fire Strike is actually a one-point wonder. The stacking DoT scales with your weapon's damage, meaning that somewhere around level 10, from the front line you can stack 12 DoT per hit for 4 Power each. The skill costs way too much power if you level it up, and the benefit is poor. This unit honestly needs a balance patch, but is quite effective in the current state if you one-point Fire Strike and otherwise build for accuracy and tankiness. If you have Summoner and Wizard, you can potentially have three different sources of burning. And you're not limited to one of each class, either. Probably does ok in the back with a bow, but the scaling burn damage will be less powerful, with the trade-off being freedom to strike the back rank at will.

Paladin is fine I guess. Haven't used much. From what I hear, the Prayer of Protection is the skill that actually scales, and much of the rest is garbage. Can also meditate for Power and Health regeneration, and has even better stats to sit in the front line while doing so. Lots of n00b trap skills, but whatever.

Bard has some n00b trap skills that get replaced by swiss-army-knife skills later on. Has the cheapest and earliest economy skills. Not great at dealing damage. If you save points by skimping on weaker songs, you can afford to build tanky. I haven't used this class much, but from what I understand, it gets better as soon as you learn the stunning song, and then there is more to look forward to further on.