CRT.5 RCM Ext chassis and othe Q's

[Sammus]

Alright, so my e-revo is nearing half completion, so naturally it's time to start thinking of another project :P
Alright, part 1) I can't figure out myself stems from this:
I have 2 3s packs (4000mah 20C), currently I run them in my rustler (MM 9L) and will run them in series in my revo (turnigy sentilon 100A HV, 11XL). so naturally I'll want to use them in my crt.5 conversion too (just the single 3s packs, no crazy power goin on here!). So now for the actual question what are the longest batteries you can fit in Mike's chassis using the battery bar etc it comes with? I think mine is about 150mm long (don't have it handy to measure).

2) What will require more grunt out of my extended CRT.5 and my rustler? I'm thinking of either buying a velineon or sidewinder 4600 combo - so even though I could figure this out myself when the time comes, which would be better suited to what do you think? (out of veli3500/sidewinder4600 and MM+9L).

and 3), I've heard of a lot of people using 1/10 2.2 rims on their CRT.5's - mainly nitro rustler rears though. Does this mean my millions of e-rustler rears can be used on my CRT too? or will the offset on the e-version be too narrow?

edit: oh and while I'm pickin all your brains, whats so good about that kyosho spur that everyone loves using?

Cheers

Sam

edit2: just realised I can get the motor mount on its own... Anyone got any ideas how big of a battery will fit on it if I fashion up my own tray? Cheers