For the speed and handling i don't know as i don't have the battery, no support in my country to buy or lease so i am still waiting for a solution
The handling should be better and for the speed it might affect a few %.
Well , for the wheels. When i looked online i saw wrong figures , the Twizy wheels are 3x98 and not 3x112 as i found on the net. So i bought Smart wheels with factory sizes front 155x60 and rear 175/50 or 55 . As of the issue with the size i modified it with the 2 cm distances as in any case they needed to go out for 2cm.