PS3 "roaming" profile?

Your Playstation Network (PSN) account can be simultaneously associated with five PS3 machines. So to answer the questions:

• Can we create profiles for the people that will play and have them exist on all the 3 PS3's?
• Can I take my home profile and use it on those 3 PS3?

Yes, each person could have a user profile associated with their PSN account on each of the 3 PS3s. You would be able to use your existing home profile.

• Would I need to keep it on a USB stick (assuming that is even possible)?
• Can I "download" it onto the machines?

Information kept on the PSN servers (trophies, list of your purchases) is automatically kept in sync between PS3s using the same PSN ID (note - you would need to ensure that trophies are synced to the server by visiting the Trophies menu item in the XMB). However information kept locally (save games, downloaded files) would not be synced. I think you can transfer most saved games using a USB stick as long as you only play them with the same account.

• What about ranks in games such as Call of Duty Black Ops, would that follow my profile or be locked to one of the machines?

Rankings are stored on servers and associated with your PSN ID, so should work fine, although you may need to copy your save games across in order to use the same character profile.

Some game saves (for example GT5) prohibit copying of the game save files. In those cases your save files are not portable.

Also, all games I'm aware of will not access saves directly from anything other than the internal PS3 storage. You'll likely find the process of copying saves around to simulate portable saves to be tedious. (IMO Cloud storage of saves really should be a feature of PSN Plus)