illusive45

I'm not new to the Nissan/Infiniti world. I still own B13 Sentra SE-R(my track biatch) and my wife owns a P11 G20t to go along with my Stg 2+ B5 Audi S4. I'm at that point where I want to get a new ride and as much as I adore my S4, its getting to the age where a lot of parts need to be replaced or are breaking down. The car is a beast even though I'm on stock K03 turbos, I love boost, but I think I'm ready to go back to NA power as long as it still gives me a similar rush that my Audi does.
I have a range of cars on my wish list from the Jag XF down to the upcoming B8 Audi S4(SC'ed) to a used RS4, but I think realistically, I want a moonlight white 09 or 10 G37 sedan w/ Journey/Sport/Navi + 7spd Auto.
I've been a fan of rowing gears my whole life, but with kids on the way, I think I'm finally giving in and getting an auto, but definitely something with paddle shift. The rev-match feature also intrigues me, but the jury is still open on how well the tranny performs in spirited driving. I'll still have my SE-R to satisfy my manual shifting fix.
I don't plan on modding the car heavily...I'm thinking just coilovers and some phat 19s. I really don't want to go further than that but we'll see if I'm happy with the stock power.

Couple questions for you gurus:
1. How responsive is the paddle shifts? Is there a noticeable lag on hard shifts at WOT? if so, is there a software flash from an aftermarket tuner to fix this?
2. What's the widest tire/wheel F/R I can fit without rubbing issues with the car lowered?
3. Are there any good chip tuners that a majority of you can vouch for and what kind of HP gains are we looking at?
4. any common problems with the V36 that I should be aware of?

TIA and hope to join "the G club" soon. Peace.