The only bit I don't know anything about is the minidisc player which strikes me as the weak link. But you can replace them for £10 on ebay easily. All it needs is a line out option

You could use Audacity (free download) on XP easily. So many options.

If you want to have more sophisticated post-copying tools there are many. Reaper (which I use) springs to mind and works happily on XP.

I wouldn't have the slightest concern

If I can help more do ask.

It's exactly the same principle as if I want to copy cassettes to digital.
Cassette player --> line out --> double phono lead to small jack plug --> line in on computer.

Then carry on

Or LPs from an old turntable