Dash doesn't need to be pulled. There are a couple of write-ups here on this forum, just need to do a search for them. It's easiest if you pull the seats for access.

Not really difficult, just time consuming. While you have it apart is a good time to renew the various seals involved.

If the core is rotted completely away and can't be repaired I have a good used one you can have for $20 + shipping.

There are separate fans for the defrost/heat side of the system and the A/C. The A/C fan is in the very front of the console and is a "squirrel cage" affair. The defrost is a conventional fan which is mounted on the firewall and yes, it is pretty weak..

You've pretty much got it figured out it appears.

The evaporator is mounted in the center box of the console. The A/C box does NOT and I repeat ,does NOT need to be split!

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