One of my PCs is doing just this. He's Lvl 14 Rouge, has a Lvl 12 Sorcerer who has a Lvl 8/9 Cleric. It's been a fun experience all around as far as I can see, and it also serves as a means to let the PCs play more than one character type over time.
On management, the DMG has suggestions on how to control what the PC can get through Leadership (p.106), but in summary it's an awesome idea if there are too few PCs, and bad idea if there are too many. Cohorts are effectively another PC under the original PC control (within limits), so it's up to the DM what comes round (hence why a PC should discuss with DM before having it go through).