CV joints/axle time to replacement advice?

[mikesz]

I have a 99 Boxster base 2.5L with a tiptronic. I need to replace the right inner CV Joint, believe me! I have no intention of spending $800 for a complete new axle. My car has about 90k miles on it. I have searched the internet and all I can find is replacing the boots but not the CV Joint. I have found rebuild kits for around $80.**** I am also considering replacing the rear axles with a used one from a car with lower miles than mine. I am a DIY and have done most of the repairs on the car myself. This includes:

replacing both coolant fans.
replacing/upgrading the brake booster with update kit to eliminate water issue this included draining/flushing/replacing brake fluid painting caliper and adding drilled rotors.
adding an S center radiator.
upgrade dash to a C4 996.
replacing seat motors and switches.
upgrade stereo/speakers.
upgrade to aftermarket exhaust.
replacing spark plugs/tubes/coil packs.
replacing engine compartment cooling fan/sensor.
replace front bumper with a 996 unit.

Some of the questions I have:

Are the TIP and manual transmission axles/CV Joints the same?
Is there a detained DIY for rebuilding the CV Joint if so can someone point me to it?
Are there differences between the axles between years? 97-99 cars, are they the same?
It seems like there is a difference between first gen cars 97-99 and post 2000 cars? is this correct? are the axles interchangeable? would I be better off getting axles for a latter model car?
Does anyone have experience with this repair? if so are you willing to discuss with me?