Rokafella

Currently working on a S13 shell I picked up with a completely intact A/C system. Seller says A/C worked up until the KA got a rod knock then sat for 6-8 months.

My plan was to clean up the shell and move stuff over from my donor car leaving the A/C system intact and sealed......

But as usual my ocd found a couple issues I would like to fix.
1: factory firewall insulation is crumbling and falling down.
2: Painting the engine bay/interior...

My Questions for anyone familiar with a/c in these cars are:

A: Is a rebuilt A/C ever the same as Factory?

B: Do I have to use special tools to empty the system?

C: Does someone still carry the O-rings & seals for a 91 240 (could not find anything other than compressor seals)

D: what should I replace if I want to completely remove the A/C for Paint and put it back in?