A question about merging or figuring out merge points

I inherited a cvs repository in my new job.  nobody knows when the branch was last merged into the trunk.  We also find no tags.  Based on other information in the build process we have a date that we guess is the last merge.  
 
A few questions:
1.  Can I see when or what date a branch was created?
2.  can I use the name of the branch as a start point and a new tag as the end point to see the changes or is that the same thing.  my thinking is the branch name will be the current snapshot of the branch.
 
If i am on the wrong track how can I see what has already been merged, or can't I? 
Sorry for bugging you.  The guide doesn't really have this much detail.
 
Thx
KM