Sakura D4 AWD questions

Hey, I have few questions for my soon arriving D4 AWD.

1. With stock Spur and TrackStar 13.5T motor what pinion gear/size would you suggest?
2. Battery mounted middle, Shorty or Regular? I'm currently thinking of reusing my regular GensAce 6000mAh 7.4V 70C 2S1P (Series with Black) what I run on my Stock 1:10
3. Tires and wheels for carpet - I have set of Yokomo Super Drift Tire ZERO One R4 (For Carpet #ZR-DR05) on Yokomo Rays Volk Racing TE-37 (4mm Offset, TW-2813) wheels what I once bought to have fun with my Stock. Are they fine to start with?
4. Is Savöx SC-1251MG Low profile servo good for it? Was thinking of 1257TG or 1258TG but they are not in stock at my local store.

As I went a bit crazy with that stuff.. I ordered bunch of Boomracing hop-ups for it from Asiatees (was able to skip Carbon this time )

• Boom Racing Aluminum Wheel Adaptors with Lock Screws With Pins & Screws - 4 Pcs Set (12mm Hex) Black
  
• Aluminum Rear Hub Carrier for Sakura D4 Rear & AWD Pink
  
• Aluminum Front Knuckles for Sakura D4 Rear & AWD Pink
  
• Aluminum Rear Lower Suspension for Sakura D4 Rear & AWD Pink
  
• Aluminum Rear Separate Suspension Mount for Sakura D4 Rear & AWD Pink
  
• Aluminum Belt Tension Mount for Sakura D4 Rear & AWD Pink
  
• Aluminum Front Shock Tower for Sakura D4 Rear & AWD Pink
  
• Aluminum Rear Lower Suspension for Sakura D4 Rear & AWD Pink
  
• Aluminum Rear Separate Suspension Mount for Sakura D4 Rear & AWD Pink
  
• Aluminum Rear Shock Tower for Sakura D4 Rear & AWD Pink
  
• Aluminum Rear Suspension Mount for Sakura D4 Rear & AWD Pink
  
• Performance Combo Package C Upgrade Set For D4 (Y Sharp Lower Suspension, Suspension Front Mount) Pink
  

I'll make separate build thread with photos, when I get my build going.

Thanks!