I've played this one and off for a while, but I don't remember seeing these specific bugs when I first started.

You can buy a courier, but you can't use it.
After a while you can't buy items anymore.
Many unique items don't show their icons.


Sometimes items can't be sold and sometimes items can't be combine.
I've found that you can drop everything and repick them up and it will combine most of the time, but sometimes it won't.

Monsters spawn points move over time... this is actually kind of cool because you can lure monsters and kill them and create giant swarms of monsters, but it sort of seems like a bug.