Can't answer everything, but i'll give it a shot.
Novak is still a save bet for an ESC. My 2 Cyclones are serving me for almost 8 years now. You can still get Trinity motors, but Motors with a V2 endbell seem to be more interesting for off road (Orion, Peak Performance, ...). Or you can do like me and go Brushless and never look back. IMHO, I would be crazy to buy a whole new brushed system these days when you can get an almost maintenance free, powerful BL system for a few quid more.
Indeed, cells go to 4200-4300 mA these days and runtime is still 5 minutes (sounds crazy coming from 1700 SCRC's I guess
). The IB cells seem to be the most powerfull, although I have the impression that the GP cells are more durable. I'm using GP 3700's. They give me all the power I'll ever need for Off-road and they can be bought cheap these days. Runtime is no problem at all. I finish in 4WD with 30% left in my 3700's.
As for the car : It's personal preference. The BJ4 WE certainly is a very good car, but I never liked modern shaft driven 4WD offroad cars. Didn't like my Predator in the 90'ies and didn't like my ZX5 last year, so I went back to the good old belter.
I also liked my Manta Ray a lot back then, so if you're a Tamiya fan, you can buy two good tamiya 4WD cars these days : If you want a full option, competition ready belt car, they have the TRF501X, or if you want a cheap shaft car with loads of hop-up potential, the DF03 (Dark impact, Keen Hawk) looks promesing. Look at them in the Tamiya section of this forum