Trail is generally more travel and relaxed (less) headtube angle. XC is generally less travel, faster steering. Of course bikes exist that throw those notions away.

It's possible to find barely used MTBs or those that never left pavement. They're a good buy. A fully beat on MTB, however, is not such a great deal as a fork needing a rebuild or bent rims are more risky.

Don't try to get a new full suspension bike for $1,000. It will have a lot of bob and other issues. They don't get sorted until the ~$2,000 price point. For $1,000 you can get a decent hardtail bike. I would test ride 29ers and 26" despite your height. Felt makes good entry level bikes, as well. Really you have a lot of options but there are huge advantages in a $1,000 bike over a $600-700 one.