This game seems interesting, but it sounds like everyone is so far ahead it would take a LONG time to catch up and everyone seems to know a lot about this game... which is a little discouraging. Is this a "no noobs" sort of thing or a "all comers are accepted" sort of thing, because I'm interested in joining.
I'm a total noob too, and i seem to be learning all right, be warned the tutorial section of the game can't really cope with the massive exp boost, so you may need to look for help with the UI.
the iRO wiki is a good resource, don't worry.
We're at a weekend or two's dedicated play.
Grinding to lvl 99 twice, second time round at half speed, sounds much worse than it is in practice.
The Eden Group gear quests will get you nearly the whole way first time and farming proper gear (and the repeatable Eden quests) will get past most of the next set with little torture (until 90+).
After you hit 3rd job i.e. lvl99-150 the pace slows down a lot and you'll be doing group content, dungeon entrance quests or farming for rare gear/card drops.
We're at the "end game" but the content is much, much slower to get through and we need all the help we can get with it.