Welcome. You will forget about your V8 Soarer in no time
Yep, you will find a heap of info on these 'ere boards...
A fair few have had the turbo replaced, it is something that you can expect to do at some time (usually around the 100-120,000km mark).
Exhaust should be upgraded anyway on turbo car, but it depends on what exhaust is fitted.
Mine was an extreme example of a restrictive exhaust and I think it is the one your are referencing.
The stock, untouched front pipe is okay I suppose (bit small in diameter though), but you really would be better off getting a 3" turbo back exhaust as the dump pipe is massively restrictive.
There are a couple of guys that are concerned about their transmissions and one has been rebuilt (damage is suspected to be caused at compliance when Dextron III fluid was used - USE ONLY NISSAN MATIC J or compatible fluid).
I personally have no issue with my transmission and change the fluid once a year (originally used Matic J but am now using Nulon 100% Synthetic ATF which is compatible).
An external transmission cooler will help (Repco stock the PWR items for around $110).
Radiator can also be undersized depending on how you drive and where you are situated.
Not really much else to be overly concerned with (off the top of my forgetful head).... just remember to post pics of your new M