kmh12177: Quick question - After you cap at lvl 50, will your followers continue to level after gaining enough xp, or are they capped when you are?
I ask because I'm level 47 and just picked up Gar using persuasion to avoid the -50 alignment penalty.
Waltorious's answer is mostly correct, I believe.
IIRC, the baseline unpatched game will stop you at level 50, and not let your followers proceed any further either.
The UAP (Drog Black Tooth's Unofficial Arcanum Patch) still caps your PC at level 50, but allows followers to level up (to level 50) every time you would've achieved another level.
The Level Cap Remover allows you to continue past level 51 (all the way to level 127, though there aren't enough things to do in the game to get you even close to that) and your followers will march in lock-step right along with you — meaning that if someone is 10 levels back, they'll always remain 10 levels behind you.
HOWEVER.
For either the UAP or the Level Cap Remover to apply, you need to install them and then start a new game;
they do not affect previously saved games.
If you haven't already installed the UAP, do so right away — links are in the stickied thread at the top of the Arcanum board — it fixes numerous bugs and potential gamebreakers, reinstalls missing schematics and unlocks new dialog options.
The Level Cap Remover is up to you; I personally prefer it, since I do so many side quests that I often reach level 50 about halfway thru the game, and then I get bored when I can no longer advance. Again, for either or both of these patches to take effect, you need to start over after installing them; but nothing says you can't finish your current game first before doing that, if you so choose.
In any case, best of luck and have fun.