Can Time Machine be used for extra drives?

I have a Mac Pro and currently have two drives in it, a system drive that's using as the startup disc and for most of my use. The 2nd drive is more like a server drive which is used on that system but also shared with all computers on my home network. i use it for things like clipart, backups of itunes from the laptops, media files, etc.
I just installed a 3rd hard drive and have been planning to set it up as a Time Machine drive for my Mac Pro. I have several questions though.

I assume when I do this it will just work as a Time Machine drive for my main system/startup drive, correct?

Is there a way I can use Time Machine for the 2nd drive in my system? In a sense setting up two Time Machine backups, one from the main drive to this new backup drive and the 2nd from the server drive to a 4th drive I can add in the future?

If the 2nd question is a No, is there a way I can set it up so that Time Machine simply backs up both the main drive and that 2nd, server drive, to the Time Machine drive? I really prefer not to use this option since both drives are 1TB and the hard drive I have just gotten as the time machine drive is 1.5TB. I think that should be okay for my main drive since it is only 30% used or so but with backing both onto it I don't think I have enough space to do it well.

Yes, you can use any drive as a TM drive, just rename it so, and select it for that purpose in TM system preferences.
When you set up TM, it gives you the option to select which drives you want to back up.
I use it to back up my main iMac drive, plus 2 externals that are always connected.