Yes, Chrome uses multiple processes.
There are multiple benefits behind it:
1) Your OS can run web apps with greater responsiveness when they are separate
2) A crash in one web app won't crash your entire browser
3) Likewise, the browser won't freeze if a plug-in freezes
4) Ultimately it limits the amount of damage an exploit can cause because it will only effect one process
Ending processes one by one will simply shut down certain apps or plug-ins that are running. One of those processes is the actual browser so it will eventually close too. You won't cause any damage by ending them.
Other browsers use up a similar amount of memory. Chrome just appears to use more because it is spread out.