Alright...... To start with, Cargo space is awesome. I've helped my sister move house, Tv's and all fit in it easy, I've also fitted a full Mugen exhaust for my civic type r in the back with box and room to spare, so unless you moving alot of stuff you won't have a problem there. Rear seats fold down flat, i can lay in the back of my car and still move around, but im only short.
Ah auto tranny, I can;t really help you with this, I have the rs4s so its a manual. Some of the other guys will be able to help with this tho.
Engine wise, all the series 2's the one your looking at has theh RB25DET from the R34GTT, power out put form factory is 206KW or 280HP. Cruise control will depend on what model you get and if it was put in after market.
Mechanical problems are the same as the GTT, turbos will blow eventually, small oil leaks (im lucky to say i haven't had any yet)
Airbags..... Ah mine has 2 in the front, but i think it depends on the model again.
ABS is standard, and Traction control im not sure on stability control isn't i dont think. Mine doesn't have it to my knowledge. i might be wrong though.... You do however have Hicas just like the skylines and also if you get a 4wd you get Atessa, just like the gt4.
Insurance.... I pay $300.00 but i have a fleet insurance (20 cars or more) but i did get a quote from Just car and i think it was somewhere in the $1500.00 mark, for an under 25 , secure parking, a couple of mods, good driving history and being female, chicks get it cheaper
Also take a good look around the forum there is ALOT of info on here you just need to have a good look around.
Hope that sort of helps