1: Im not sure on that, probably find out through Wiki tho

2: Alot dont do it often, but Fenrir does it alot

3: The level cap has been removed on all missions so you can level up and solo them all, any job will be good enough by the mid lvls.

4: With Abyssea Gil is a cake walk to make now, for every 1 Cruor you can turn it into 2.5x gil with Chocobo blinkers (e.g.: 100k Cruor = 250k Gil) and Cruor you can make about 40-80k an hour in a good EXP/Dom. ops party.