Do I need to remove the old glue from the rim before applying the new glue?

no, unless its built up quite a bit. Scrape it off the edges if you're worried.

Cool, that'll save me a lot of work. thanks.

http://www.velonews.tv/ Look under the "How To" section about 2-3 pages in, a pretty decent set of video-articles on the subject.

i like to ensure the brakepads aren't contacting any old glue residue.

but why? it smells so awesome when it burns off.