Aside from DEF / HP / mitgation buffs from character skills, summons and weapon skills, it's really the base multiplier from your weapons and summons that go into stats. And then there are healers obviously.
The story Catalina (blue chick with a sword) has both a heal, and a 50% flat mitigation skill. Use the mitigation when a boss is about to use his skills (diamonds filled up and flashing), and that should keep you going for a bit.
Here's a list of all the jobs and their skills (missing the newer classes, but still useful). I made a beeline for the Tier 3 thief to get the treasure up ability, but there are a lot of choices for progression. Do note that JP acquisition slows down considerably when you get to rank 40ish and leveling up takes longer, so don't blow all your JP thinking that you'll get lots more. You have enough to go straight for a tier 3 job quite easily, but your 2nd tier 3 will take an extra week or so.
You have to fill the 750 points to keep your event character, otherwise he'll go away after the event ends. These screenshots are for the previous event character (which needed 1,000 points), but this is what you need to track. I think it's tied to exp, so just run the usual dungeons, and it'll go up.