He could get caught up on drug/weapons charges again.
People can't be pardoned for future crimes
Pardons for unspecified past crimes for which charges haven't even been brought yet are of dubious legality and haven't really been tested in court.

@JonathanRay the pardon at question Ex Parte Garland was fairly specific in that it only pardoned people for participating in the confederacy, not for all possible crimes. The latter sort of pardon has only ever been given to Richard Nixon and Hunter Biden, and hasn't been tested in court.

He could easily commit another crime in the US and be sent to jail. The pardon is not prospective. I imagine Trump will be looking for any opportunity.

Yes

Some questions:

1) Does this include the past?

2) Does it include visiting someone else or being in a jail for other reasons?

3) Does it include both jail and prison?

@Joshua
1. No
2. No.
3. Yes