Yes. Yes it does!
If it's a spring shotgun(which i assume it is) then the weather will not affect it. If it uses gas, then yes.
The color of paint does not affect gas mileage in any way.
Yes, the faulty power steering pressure switch does affect the gas mileage. It will give a wrong reading of the gas mileage. It is therefore important to fix it when it is faulty.
If it is malfunctioning it can affect fuel mileage.
Yes.
You can play airsoft in any weather. Airsplat.com has Ghillie suits and vests to keep you warm in the cold so you can play airsoft at anytime of year. Check out Airsplat.com for airsoft accessories and guns.
YES YESYESYESYESYESYESYES
yes
incorrect tire inflation
the lower your rear axle ratio, the worse your mileage.
No, not really. Any increase in mileage will be minimal at best. Far outweighed by the cost of the cold air system.
All of the engine sensors can affect fuel mileage.