Apps and passwords stored in keychain I did not set up

I appreciate you patience if this is a stupid question, but I am just trying to understand security basics and how somethings have appeared in my keychain.

I have never used facetime, iMessage, jabber or GameKit, yet they all appear in my key chain. Some with my actual password and id, others (auth-tokens I think) with my id and some incredibly complex password, all for services I never set up directly. Is this part of the automatic set up on mountain lion?

Gamecenter shows up in console as ignoring User and Group permissions, yet I did not activate game center..

There is also a com.apple.scopedbookmarksagent.xpc that I did not set up and does not show a password when I try and view it in the keychain app.

Are any of things normal? Are there any security risks here?

I would just like to know for my own education and peace of mind and would not want to accidentally delete something that is important to the function of my machine.

I would deeply appreciate some insight here.

Thanks!