Collaborative tools for dummies/professors
First off: If your are interested in real-time collaborative editing, try something like gobby. It lets you literally edit a document at the same time.

As for revision systems, I am only familiar with SVN. This is what you do, after installing subversion, of course:


Get someone to set you up a repository and give you URL, username and password
Go to where you want to have your lokal copy
In a shell (command line?), type: svn co url://to.your/repository (check-out). Now a new folder with the repository's contents appears.


That's all. Now the most basic commands:


Whenever you add a new file foo, enter: svn add foo
Whenever you want to remove a file, enter: svn rm foo
Whenever you have made changes, enter: svn ci (check-in)
Whenever you want to get the newest stuff, enter: svn up (update)


There are also commands for moving, copying, branching, resolving conflicts,  ... but as long as you do not try funny stuff, you are fine with the above. If anything breaks or seems to, backup your edits, delete the whole folder and checkout the whole thing anew. That's for svn like rebooting for Windows.

Addendum: I see you seem to be concerned about "smart merges". I assume that you refer to have to different versions of a file merged, with the assumption that two people added things in disjoint parts of the paper. As far as I know, svn would treat that as a conflict, and probably rightly so. I don't think that there is a general procedure that ensures you get what you want after two people manipulated the same source. There are graphical svn clients that visualise such conflicts and help you resolving them; they are pretty much diff-viewers were you can choose which version to keep for every conflicting line). It will require work, though.