Only have 9 sites at the moment and maybe keeping it that way as they are quite hard to run from time to time may get some self ran sites.
Well I have only one site and that is a blog @ dailyapps.net. I update it daily, and yes I'm currently using Adsense on it, but am not satisfied with the results..
Yes it does but when u have money to spend they u can always hire someone/or a group of people to manage all the sites thats how it is done
Only one forum. [it's in my siggy]. And yes, I do use adsense on it. But that's not the only source of revenue from that site.