Hi Jad welcome to Motoredbikes! The guys say it is luck of the draw with the HT kits and you usually need to tinker with them. The simplest kits are the friction drive. do some searching and a lot of reading here.
nope, the engine fits in the center where the suspension is
a rack-type (over the back wheel), either friction or sprocket/sheave driven. is all that will fit in that frame configuration