I would guess (hope) that ffxi grind style parties are still viable in xiv. They were a big part of 1.0 and though there are many other leveling options available like quests, dungeons, hunting logs, etc hopefully grinding is still an option as well. I had a lot of fun in spiritbond/xp parties in 1.0 and hopefully we can still do that if we chose to.
It's good to know that I can solo to max lvl as I don't have a lot of time to play
. I do miss the fast pace DD burn party in ffxi.
They are catering to this. People who played the crap out of FFXI back in the day are now in there late 20's and 30's. We all have lives. You can 100% solo all your jobs if you like but the fastest way to get exp and gear is through dungeons and FATES. However, you can still "solo" those by using the Duty Finder. All you need is 20-30min of time to complete what ever even you want to do and then log out. Very casual friendly.
What kind of bonus do you get? Does it depend on the party size?
Open world partying is pretty much FATE hunting now, which you can also do solo.
However you should group up, as most people don't understand ther eis a large XP bonus for being in a group.
On the other hand, you can't DF queue and be in a group.
You can get an EXP bonus, attack bonus, I think treasure hunter effects, etc. The size does matter.... too. 4-7 people is a light party and gets a moderate bonus where 8 people is a full party and gets a bigger bonus with additional effects. What those are for each group, I think they changed them for ARR. You will find out soon though.
Hope that helps.