I've been using the Linux version of Lilypond for the last couple of years, and have had no problems in downloading updates - as Noel hasn't had any difficulty, perhaps this is a temporary problem with the website.

I don't know if I want to volunteer as an expert (defined in the pre-PowerPoint era as "someone from far away with slides"), but I'd be happy to help anyone out.

There's a program called BIABConvert out there, which says it will convert BIAB files to LilyPond's format. It does this up to a point, but I found I needed to do a lot of editing afterwards, and ending up just typing in the parts.