[Linada]

I have come from Life Balance as well.
GTD and the life balance system are really quite similar. What Life Balance tries to do that OmniFocus doesn't is the prioritising part, in GTD parlance the higher horizons of focus. Basically these are the top level items in the life balance outline.

There are various ways in which you can do them in OF. You could have folders and subfolders until you reach the level of completable projects, or you can just have several layers of sub projects, which is basically what LB does.

What you can do in OF that you can't as easily do in LB is postpone things.
You can out entire projects on hold for infinity. Stuff that you want to do, but aren't sure when yet. Travel the world, learn japanese, etc.
You can use start dates. Not as easy to filter for in perspectives for reviewing, but more in your face when the time comes.

For resorting your contexts there are several options in the view bar. Grouping and sorting are the most relevant ones. If your context list are unwieldily, no matter how you sort them, you might need more contexts.

Don't be afraid to do a lot of shuffling. I always need to give myself plenty of playtime with any new tool/toy :)