Personally I'd run a Sturmey Archer front drum hub, it's a beautiful vintage motor and a drum look a lot better then a disc, but I'm old school and it's just personal preference.
I'd run a coaster rear brake so you don't need to run dual levers and less messy cables. In my book less is more.
Isn't your friend going to teach you to weld or at least help you, so you can easily make stuff like a layback seat post for next to nothing, and best of all you can say you made it.
Depends how involved you'd like to get, but my Villiers build will need similar parts as yours. And all I bought for my bike was bearings for the jackshaft. The rest I made from bin finds and parts I already had. It wasn't hard and there is no reason you can't do the same. Up to you, but I'd be more then happy to help you any way I can. If you do most things yourself you will enjoy your bike more and have a unique bike