1. most will say yes. it just simply helps leveling your following jobs easier till you run out of quest and have to resort to the grind route of options.

2. most would recommend that you should get your subclass to 15 so you can get your job at 30 then take it to 50. will make life easier. but play how you want.

3. somewhat. melding, hq gear for leveling and/or the endgame isnt too bad. also housing items. not a high demand but better than before imo.

4. daily roulette and challenge log have been implemented to make leveling, gil farming, chocobo leveling, and tome gaining a bit less stressful. beastmen dailys. helps with exp and tomes as they are repeatable. they also lets you buy mounts/minions at max rank. treasure maps, gained from lvl 40+ gathering classes. can grant rare valuables. housing, if you have the gil is a fun time waster.

thats all i can think of off the top of my head. just remember to have fun and it helps to find a group of friends to play with. welcome back to Eorzea