Well, I'll cover off the stagea side of things.
The M35 stageas started in 2001. From 2001-2003 the eligible models are all turbo. They run a vq25det 206/400nm. The chassis is very similar to the v35/z33, meaning it can be upgraded to handle quite well. Being turbo, power is reasonably easy to extract. There areafewweak points.the stock turbo is fragile, the afms temperamental, and the motors cam actuators wear with age. There is no ecu flash option, so people piggy back them when tuning, which is a bit tricky. A properly sorted m35 will walk a v/zin a straight line.
The second series, 2004.5 on have the same motor as the v/z. Vq35de. There was some styling changes, and some changes to the awd system, and interior update. It has a flash able ecu, and doesn't have the issues of the first turbo series motors.
The models go RS then RX, then AR-X, the later having the over fenders and stock 18s. Then there are Axis models, which have different interiors, but no mechanical changes.
The v35 is more of a GT car, while the Z is more of a sportscar.
Drive them all, and see what you like