There was 1 shop keeper at the top of the inn, as soon as I bought from her she stopped selling to me. No other shops actually buy or sell anything. Does this end at some point? Or did I break something?

There are several NPC's around Cyseal that sell goods. Most will keep a consistent inventory throughout the game, but I do believe some refresh some items every now and then (when you level up, perhaps? Still figuring that part out.)
There is a small market just south of the inn, but also you should make it a habit to see what each person you talk to has to offer. Every now and then you'll find something interesting on a commoner, though many folks will either have nothing to barter or next to it.

There is no option to buy or sell from anyone, in all of Cyseal. I am wondering if I broke something.

the characters that act like vendors in center of town, no buy option. shopkeepers, no buy/sell option.

Thank you. Here is what happened:
When I first got to town, exploring the inn, the vendor on the top floor had a text option to "Shop". I expected that to be the usual method to shop from that point on (dumb), and didn't notice the shop icon. Entirely me being dumb, but with a reason behind my dumbness...

There is no problem with the game, it was entirely me. thank you again.

Glad you got it working! :)

For what it's worth, I've encountered a few characters who have nothing in their inventory but you still get the option to trade with them. Maybe it's to allow you to give then goodies for free. I haven't found anyone yet with whom I didn't get the trade icon.

Though on second thought - and I haven't yet checked this - maybe they can repair or identify stuff for you...

I've actually tried giving something to one NPC that had the "shop" option but had nothing to offer, just to see if maybe it would raise my reputation with them or something. I only tried it once, but I didn't notice any effect. I wouldn't be surprised if there were NPCs you could benefit from giving gifts to though.

As a side note, I really like the fact that all NPCs keep everything you ever sold them. Comes in handy when you realize you've sold something you thought was worthless at the time, but that comes in useful later.

Even in DD, I never noticed a chance in behavior ("shop" prices) from gifts. Maybe it comes from repeated gifts over time. What did help with pricing was repeat business, and I suspect DOS has a similar formula since my revenue from selling stuff isn't so horrible as before.

And gonna take note of that second tip.

I also need to play around with using crates / barrels for permanent personal storage. I know that unexplored crates and barrels have a random element, in that the items can change with a game reload, and I need to see what effect that has on items the player places into storage.

If you mean you're worried that stuff you personally store in crates and barrels may change upon reload, don't worry, it won't. That only applies to things like crates, barrels and treasure chests that you haven't yet opened. So, if you were having trouble getting decent gear and felt like reloading a bunch, you could quicksave just before taking the turn that will land a killing blow on a boss, or right before opening an ornate chest (or a metal chest, as those often have great gear)

Once you get your homestead, it's nice to pick up a few chests (I prefer the ornate chests, as they're just fancier looking, hehe) with a character with high enough Strength or Telekinesis, then teleport to your homestead and set them up where you please. I have a few in my homestead, one for blacksmithing goods and gear that's too high level, one for potions and potion supplies, one for spellbooks, scrolls and scroll/spellbook crafting supplies, one for food and so forth.

**I apologize if any of this comes off as spoilers... I never know what's appropriate to share in those regards. :)

After playing around a bit, I'll say that it can definitely benefit you to occasionally give some shopkeepers some junk loot for free sometimes. :)

Nice! Goodness knows I have plenty of garbage sitting in the ol' inventory...