Tafferwocky: Really helpful, thanks! Will dying restore your hunger to zero then? I've found a green potion, but don't know what it does.
I actually don't remember about the dying and hunger interaction; it has been a very long time since I've starved to death (and that sentence didn't feel awkward to write at all). I'm inclined to think that dying doesn't reset your hunger level in any way, since the scale runs from "Starving" to "Satiated". One way to find out!
All green potions look identical, and all red potions look identical. Note that they aren't all beneficial (though the potions of Hallucination can be amusing). There are several different ways to find out the effect of a potion:
1) Have a high enough Lore skill. Note that there is a random roll involved in identifying an item, and the roll is made when you right click to see what the item is. If you have a decent lore, and you aren't opposed to save/loading, then you can save just before looking at a piece of equipment, then reload several times until A) it identifies fully, B) you are content it isn't magical, C) you are content your skill isn't high enough to id it, or D) you get tired of reloading. Be advised you only get the one roll unless/until you raise your lore skill; extra right clicks will use the same result. Sometimes you get a partial id ("Magical green potion"), instead of the full name ("Green Potion of Restore Mana").
2) Use the "Name Enchantment" spell rmeakins mentioned. I don't know the rune combination off-hand, and I don't think it is specified in game. I can dig it up if you like, if you don't want to risk running across potential spoilers.
3) There is a single wand of "Name Enchantment" to be found. If you aren't adverse to save/loading, I'd advise saving before using it, then reloading. The wand has a limited number of charges, so it will eventually break if you don't preserve the charges via this method. Using this is an easy way to tell whether or not something is magical.
4) There is a mage on level 6 that will identify items for you, but he charges gold. While there is a lot of gold in the game, it is not in infinite supply.
5) Drink it and see what happens! Obviously, you'll need to save/load for this to be a useful option, and it may not always be apparent what effect the potion has (ex. if you aren't poisoned, then you won't be able to see the effect of a Potion of Cure Poison, regardless of how often you reload).
Method 5 (try to use the thing) won't work for all potential magic items. Most weapons and armor, for example, have passive effects.
stryx: The shrine on the second level is much easier to access, so there's no need to come back to the shrine on the first level.
This is true. I go into that first shrine area once, just to add it to my map. Then I leave and never come back on that play through.
Tafferwocky: While I'm at it, does Lore also help you see the power of armour and weapons? At the moment there's no way of telling how good items are.
Sadly, no. Lore is useful for telling you whether something is magical as well as what the specific magic power is called. It won't tell you what that power does (though the power name is usually self explanatory), nor equipment stats.
Better equipment is usually better at its job, but it is also usually heavier. Stronger weapons take longer to charge to full power as well.
Plate > Chain > Leather > Nothing
Tower Shield > Wooden Shield > Small Shield > Buckler
Broad Sword > Long Sword > Short Sword > Dagger
Battle Axe > Axe > Hand Axe
Flanged Mace > Mace > Cudgel (I think, not sure about this one)
I'm not sure where jeweled equipment fits into the rankings.
Weapons and Armor also have durability. Excellent > Serviceable > Worn > Badly Worn. This stat doesn't affect weight; I don't know if it affects the damage/armor value of the equipment. If something takes damage while Badly Worn, it may break (and be lost forever). With the Repair skill, you can repair most weapons and armor yourself at any anvil you find, though you may also damage them if your skill is low compared to the item in question; it is much easier to repair leather than plate. You can't repair jeweled equipment.
Shak will repair any weapon or armor (including jeweled) to Excellent for a price, but he won't work with anything that is Badly Worn ("goblin make, no doubt").
You'll need to balance the weight of your equipment against the general effectiveness of it. For example, most of the time I don't worry about wearing plate armor (too heavy), sticking with chain as a good balance between protection and being able to carry something besides the armor. For weaker characters, I may stick with Leather instead.