pedal brakes

Yes. Most coaster brake rims accept the ragjoint sprocket with no problems while retaining the coaster brake system

I had to mod my sprocket to fit the coaster arm for my Histop rim, as well as tweek the arm itself to clear the rag joint bolts.

Yes. You may need to bend the coaster brake arm a bit that attaches to the frame. Using a coaster brake means you need one less lever on your handlebars. You should add a front brake once motorized. Most add a bmx style rim brake to the front and some add mountain bike rim brakes, discs and drums.

The easiest way is a sprocket adapter. Another easier way(some might not agree with but worked fine for me). Remove the dust cover behind the brake arm and mount the sprocket right up next to the spokes. Then trim the dust cover a little so it will fit and put the brake arm back on. Some worry this will put too much stress on the spokes but I never once broke one. Your going to have a little less chain/ tire clearance like this and might have trouble clearing a 26x2.125 tire but can be done and no need to bend the brake arm or enlarge the sprocket hole. Or, you could maybe order a prebent brake arm from pirate cycles if you don't have the means or skill to bend it yourself. Just passing on info. If you want advice? ask norm

I was able to 'custom' bend my brake arm to make it work. Clearance is very close, but it doesn't rub.

If your bike only has the rear coaster brake, you'll want to be sure and add a front brake. Really.

Good luck with your project!!