1.) Increase overall EXP gain for a set duration (Until SE deems it ok to lift it when the craze is over)
Are you taking advantage of food and Sanctuary bonus... doesn't take much to get a 50% bonus to your xp/kill, especially if you have a job at 50 already. Was tooling around on 36 PLD tonight with my Choco and pulling in 300-400xp/kill soloing leves--and these weren't even the proper level, was just doing it to spirit bond a few odd pieces waiting for a fate on daily hunt list. Imagine if you formed a group that could take on a level gap to maximize your xp, and you just burned the xp chains old school party style? Might even manage to have some fun, and maybe make some new friends... you know, like we used to do in MMORPG's. Just a thought or two....
2.) Increase EXP gain from Fates (Gil and seals is optional)
Are you doing level appropriate fates? Reward scales according to level difference above/below the recommended level. Don't forget the chaining FATES as well. There are some that can rack up nice chunks in some zones.
3.) Increase EXP gain from Leves (Battlecraft leves only, seals and gil is optional as well.)
Again... are you doing level appropriate leves? You can also adjust the level upwards for bonus xp, and get time completion bonus as well if you do them quickly.
4.) Increase EXP gain from Quests (Again this one is optional)
XP from quests has always been a bonus in my book. Since nearly all of them are non-repeatable, they shouldn't be a staple for leveling anyways--they are for story progression or item acquisition more than for experience points.
As for the issue with getting into dungeons. As others mentioned, you can pre-form. Doesn't even have to be a full party. Can team up with a friend and one of you takes a job in demand, and then you swap roles and run them again. Done this with just one other person playing as a healer or a tank while I was on DPS and it was often a near instant queue when I was staring at absurd queue times in the past.
The point is, there are already ways to improve your XP progression speed if you put your mind to it. Are you doing all that you can to maximize xp gain within the current system?
By the way... what's with the rush? I spent all night doing various things and saw player after player already at level 45-50 NIN. Had well geared lvl 50's hopping in/out of a hunt party for about 4 hours earlier this afternoon. It's only been freaking 3 days for heaven's sake.