As to your first question, with respect to products that I am no longer offering I have done one of three things:

1. If it made sense to simply offer a similar product, I would simply change the page and keep it.
2. If that wasn't an option, on my old system, I would simply sever the link and I would keep the page.
3. On the new system which is database driven, I simply 'hide' the product but keep it, which is the same as severing the link to it.

You could of course do a redirect.

Like yourself I saw in the logs that google was trying to crawl pages that didn't exist. On one site, which I picked up off of the expired list, I saw that google was trying to crawl pages from the previous owner and I went out of my way to build content for those urls it was trying to crawl, figuring that if google was going there I may as well put something there for it to crawl and cache!

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