I got in to the city, went out to get wolf pelts for the hunter, and when I went to re-enter the guards want a bribe or won't let me in. Is there a way of being let if permanently? Or does that come later?

Did you commit a crime before leaving the city? If you commit a crime and then leave the city the guards charge you to let you back in. If that's the case go and see Lord Andre (the paladin guy in the militia barracks) and he'll tell you how much the fine is, and after you pay that everybody is happy again.

EDIT: also note that there are ways of getting back into the city without paying the guards (e.g. diving into the ocean and swimming to the harbour).

Of course, then, you'd have to sneak in (several ways) or pay the bribe to see Andre.

Yup, that was it! I hadn't realised I had been seen and had a fine waiting for me. Paid that off and suddenly I don't have that problem. This is a VERY unforgiving game, I am loving it!