Just get ready for a ball of fun. Haha..you seem pretty knowledgeable regarding the basics. The adult stuff eats up bandwidth, and the mainstream stuff is way more mild.
If you're going to advertise, start working on your methods there aren diversify. Since you have available bandwidth already, I don't know preactive you'll go with ads, but just have a good plan all the way through and don't rely on any one source of income too much.
The big pain with freehosting is dealing with abusive users. Phishers, scammers, and spammers can really cause problems and increase the need for an effective abuse handling process. Stay on top of complaints, and any methods you can employ to prevent abusers from signing up, do so. Figure out your stance on other points, such as whether you want to allow hotlinking, or not. What kind of warnings do you give to users, are you going to maintain inactive users' sites indefinitely, or remove them after so long to free up disk space. With your custom scripting, be envisioning ways to sort and filter out abusers. People using the space to store or distribute mp3, software cracks, or other contraband take up a lot of space, and if allowed to proceed without any stops..they will multiply quickly. If you allow FTP, be aware of some groups that share FTP passwords and use quantities of bandwidth without even crossing your http pages.
Well, there are lots of other key points, but you get the jist of it. Do you best, try to plan ahead, and get lots of hits. That's the best part with freehosting. Converting those hits to something useful is the next level.
Have a great day,
Chad King