Hello & Welcome to the forum.
A lot of the info for these is hard to come by, I don't understand why since so many were built already.
I'm not going to completely answer your questions but will give what info I can for now. I'm starting a build and was going to try to document it.
1) The semi parts from Project Guns (also a member here, Pirate) is either $125 or 150, it is based on the Wise Lite Arms design but I've heard there were some minor changes made to better the reliability. I don't think it comes with directions, unless that changed recently.
2) I never heard of any complaints about the shorties, you should be good to go.