I like doing accents and impersonations of people, I just dont want it to be taken offensive, is that bad?

Not bad when done in an informal moment. Don't imitate the accent of the person near you, unless you know them well, otherwise, it seems jerky. Also, like anything, people have a hard time finding something wrong with things that are done well. If your Welsh, Scottish, jamaican, Spanish, or japanese accent is spot on, the less likely anyone, even people with that accent, will be offended.

It depends on the moment. There's a time and place for everything. If you are doing it to mock someone then yes it's bad. If it's just for fun and at a good moment and people get offended, then maybe they are just uptight.

That's good. It's important to have a sense of humor but not at other people's expense.

I bet you are very good at it.

Hope this helps