boxster 2000 , installations

advise-
I would like to upgrade some things on my 2000 boxster.
Would my year boxster be able to handle a newer model PCM from any other
model porsche 2000 or higher? I'm looking to get a used one(PCM), any
hint on finding it. also. has anyone fitted their boxster 2000 w/
heated seats. I have heard it is equiped, and all I need are the
switches is this true? One last thing, has anyone tried the smart top
module? do you like it? actually, I'm kind of upgrade crazy at the
moment. I also want to get the speedster humps and larger wheels.
is 18" the largest that wil fit my roadster. I would love to get the
19's but the manual says 18 is it, is this true? basically, i'm
looking to get all of the boxster S options on my normal model boxster
2000. The last thing i would love to get would be the RED brake
calipers to top it all off. Any advise would be greatlyappreciated.