Advice on proper use of CVS

[Pico Geyer]

Hi.

I have the following scenario:
A member of our team is updating one of our build files (build.xml).
Problem is he has made mistakes and committed them to CVS, now none of
the team can build their code.
I guess we should be going back to the old version until the problem is
fixed.

What is the proper approach to this?
This is my game plan: (Comments/advice/corrections welcome)

cvs -Q update -p -r 1.7 build.xml > build.xml (1.8 being the latest
version)
cvs ci -m "reverted to 1.7 code"

Now we can compile our projects again.


We should now all have version 1.9 after doing an update. Now the person
needs to fix the error so he must get version 1.8 .Here is where I'm
really confused.

cvs -Q update -r 1.8 build.xml

Will he end up with a file that is exactly the same as version 1.8 or
will it be a combination (merge) of 1.8 and his local copy?

One more question:
If I make changes to a local copy of a file, but want to discard them.
Should I just delete the file and then run update on the project?

Thanks in advance.
Pico