||1. Nope, just makes it harder to find tuners for it.
2. I would stick with a 92 ECU.
3. A lot of vendors also offer a core charge, where you would have to pay the core fee up front, but wouldn't have to ship your old ECU out until you received the new one. If you need someone else to socket your current ECU, I can usually do it the same day I receive it and have it shipped out the next day. I generally create/burn/sell chips for $50, or chip + socketing for $100, but if you just need socketing I'd be happy to do that for $50. (shameless plug). This would also allow you to pick up a SZ EPROM if you prefer to run their chip (which I think is like $100).
4. Not any good reason :)
5. Sorry, I honestly couldn't tell you :(