If you are going to need to add multiple switches, it all depends on how. IE if you want to run a drop to a/many room(s), and split there? Several smaller switches at where each drop terminates is preferred. If you have them all in the same room? One larger multi-port (4,8,16,24,48) is preferred.
Don't get a managed switch unless you feel the need to program it, unmanaged is usually more than powerful enough for home use. If you are going to use Power over Ethernet (IP Cameras, access points etc) make sure you buy a switch with that capability.
Vendor? Any of the standard vendors work, netgear/dlink/belkin are common in SOHO applications.