bike build info

I am getting information to start building my first bike and I need a few questions asked. I am looking to build a bike with a Briggs stratton motor. I saw the plans to build a bike with the motor with the briggs motor but with no cranks. What are the advantages with the cranks, and without. I see that some people either bend or make there cranks to clear the motor. I would guess they use the cranks to get the bike going. All the smaller china motors use the cranks to get the bike rolling then the motor takes over. That was question number 1.

With those plans that are posted on this forum. I will post the link. They use a belt drive system. They weld or bolt a 2nd rim to the rear rim and that is what drives the bike. What is better, belt drive or a chain drive like the china motors?

Here are those plans....
http://www.vintageprojects.com/mini-bike/Power-Bike-plans.pdf

Thanks for the help..

i picked up a schwinn cruiser a few weeks ago. Not a old one but a new one. I picked it up for $30 and everything works. I would just need a new cable for the shifter. I will have to get some pictures asap. I also pick up a few months ago a old briggs motor. I will have to get my friend to help me get it up and running if it is worth it or not. I pick that up for $20. I am looking at stretching the front a few inches to fit the motor and getting everything else l figured out. As for the motor placement I am still looking for a few ideas.