The environment here is a purer unix structure than the more common "cpanel webhosts" catering to the shared market. Out of the box, users can edit/control their own space only. You can setup UNIX groups to allow sharing of files, but for the most part the user is the only one who accesses their space without some admin'ing on your part in the backend.
I read when moving here that you can request, without explanation, that your account be moved to another server. Unfortunately I didn't keep the link to that particular blurb, but contacting Sales will put your mind at ease regarding that.
That means for the life of the account. If you keep the account active you get account 'credits' each year end that may be applied to things such as re-registering, or transferring, or creating domains.
You can edit A, CNAME, TXT, MX, NS, SRV directly in Panel.
You have infinite plus disk space. If the website points at the content there should be no contention.
Highly unlikely, unless you were breaking the TOS (copyright, etc.)
If you're breaking the TOS you aren't likely to be warned by any provider.
Dilligently.. and with a very big stick
Honestly, I don't know as I've never had to deal with abuse claims, and the ones you read about you only ever get the perps side of the story. The ones who have made a bit of noise after the fact (at least around here) have invariably been punted for obvious and blatant abuse.
DreamHost is a really good provider all told.
If you want to check out the Panel PM me and I'll setup a user for you to have a poke about with.
Maximum Cash Discount on any plan with MAXCASH