i recommend liberty too. i like it better than apex and it's about to get an update.
as for the launcher change mentioned above, you can change the launcher whether you are rooted or not, or running the stock ROM or not.
The three main launchers i know are, GO launcher(i use this one and its my favorite of the three), ADW EX launcher, and Launcher Pro/Plus. They are all faster than the stock launcher and offer many of the same options between them with each having its different looks and tweaks to make them individual...
my recommendation is just try them all out and see which you like best. it's probably best to give them a week each so the programs settle in a run stable while you are using them...