how to read/write block parameters with Autocad2000 and VBA

I would have to see exactly what your work looks like to give you detailed advice, but it sounds like you might want to consider using XRefs for the material that doesn't change. You need to think through the advantages/disadvantages for your specific situation before deciding, though. Remember that changing the XRefed information changes every drawing that is referencing it.
Beyond that, template drawings should work well, also. The help files should provide plenty of info on that topic. If your files are relatively small, this might be your best solution.
Unfortunately, I haven't found a really good VBA site for beginners. I've bought two books specifically about VBA within AutoCad, one by Joe Sutphin and one by Phil Kramer. IMO, Joe's is a much better and more copmlete reference, but for a complete newbie, Phil's was quite helpful as well.
Autodesk has a VBA specific newsgroup with some very knowledgeable regulars that are always willing to help. I've written a few things that deal with Excel, though I can't say I'm very proud of them. One works quite well, though it has it's share of problems as well. If I get the time, I'll try throwing together a simple example, though I can't promise anything.
Neither seems to be an issue. ;)
HTH