Friends Request

Are they offensive. Or maybe to the point. How do you convince the recipient it's a chat to start with..

In themselves, no- a friend request is just that: a request, however I think you'll find most people are reluctant to accept one from someone they have had no previous contact with at all and see it as a bit weird, but YMMV...

I've asked this before but not had an answer.
What do you gain by being someone's friend?

Interesting question- do you mean philosophically or specifically on the site? I'm going to assume the latter- basically it gives you an easier way to stay in touch with them, along with some people choosing to set privacy filters to include friends only, in which case you're inside that filter. You'll also get notifications for things like profile updates and status changes, again depending on individual settings. On top of that, you've got a friend, which can never be bad, right?