Crist is safe for '18 and '20. Obviously it's impossible to know if he'll get screwed or not in the next round of redistricting.
I doubt redistricting will become an issue for Crist. There's really no way to change the shape of the district.
If Florida gains the 1 seat it is expected to, yeah Crist's district should be fine, if it gains 2 which is a possibility, it could get changed pretty easily.
it really can't. pinellas is pretty much built out at this point, and the court's rejected water continuity for this district as a fair districts violation in the past. there's really no other shape you can draw here.