You can. The main issue is that the general store in the village has no stock. You can buy stuff... mostly just fine (some items are a bit bugged, such as buying cloth or leather) by climbing over the gate in the village, and going to the main city. There's a general store there that works (mostly) just fine.
Could not when I played it. Maybe it was a bug or something, but I was there from open to close trying to get a shopkeeper to interact with me.
The vast majority of them can be spoken too. Try the Inn, and choose to speak with someone. Only issue with it, is that 'who' you talk to is random. But, I've spoken to the blacksmith, vendors, and several other village citizens by just chatting at the Inn.
Same deal as above.
In a word; yes. Combat works. Does it work well? No. You'll always be outnumbered, you cannot chose 'who' to attack with each strike, and after a few attacks it makes the mob you're fighting poof from the combat list, and you'll be stuck spamming attack until either they 'die', or you do. Dying lets you rebirth. But, that's bugged too, apparently.
the glitch causing stats to not update made any interaction from combat impossible to recognize. So all I got was hit strike until it tells me I lose or won, then nothing happens after.
They do change. However, for some strange reason Mana does not seem to recharge above 1, and if your hp drops below 60 it will never heal above 60 again, despite having a max health of 80. Energy is stupidly easy to manage. Sleep, drink from wells, etc.. Pretty much anything that's even remotely relaxing will restore your energy.
Again, not my experience. The stats at least visually always stayed maxed. At one point I spent like a week diving at the pond to grind endurance, and nothing happened, so energy atleast wasn't draining properly. And I did manage to get my mana to increase to ten, but I don't remember how. Once it got there, it never went down.
It's buggy, but mostly functional. Dev said there should be a major content update dropping in about a week. So, just keep the thread on your watch list. It's supposed to address several of the issues.
I fundamentally disagree. It sounds like several of the issues I encountered, you didn't. That's great for you. But for me, the game was entirely non-functional.