I'm kind of starting to get the hang of XML and stuff and extended some filehashing program to export/update an XML file and then made a little stylesheet for it:

http://darkfader.net/temp/URI%20generator.png

It outputs magnet URI with sha1, tiger, ed2k and filename.

Any recommendations of how to add size,crc32 and other hashes to a magnet URI?

Encoding schemes etc.

What about P2P-client dependent sources?

I think the magnet-uri page should be updated bit.

Looks like an interesting tool!

There isn't yet any standard way to add a length parameter to a magnet-uri, but discussion at that list may generate a proposed way soon.

I don't believe there would be any compelling reason to add a CRC32 to a magnet URI that already includes any truly secure hash; it'd be redundant/useless info, and reliance on CRCs for most purposes should be discouraged.

Don't understand your other questions, but feel free to follow-up with more detailed queries here or (even better for magnet-uri topics) the magnet-uri discussion yahoo group.