ok, my brother'* AC compressor is making a metal tinny noise indicative of the clutch material fading (sounds familiar, right PeterG?)

I am going to be replacing it because my brother is whining and our mechanic is on vacation. Having done the AC compressor on a 92 L67 on the side of the highway, I know what is involved, but have a couple questions about the L36 differences and post-replacement.

First, are there any differences I should be aware of? They look to be the same, so that is a plus.

After replacing it, do I need to recharge it? The car currently doesn't have air we believe due to a leak in the firewall area.

If I need to fill it, what would be recommended?

Working air is not necessary from this as it isn't working currently, but getting rid of the sound and the chance it will go is.

Thanks

Just change it out. Easy job actually. His car now has AC (for now) which it hasn't had in 2 years (thought it was a leak inside, hence the doubt.)

Going to take it for a drive tomorrow and check it out again.