i cant answer all your questions but yes you can do leather work without any machines. Add a stitching pony or clam to that list. It is hard to sort through the redundancy of tools for sure you will get any number of answers why one type is better than the next. Many of your wood working tools will come in handy as well for example your scratch awl, small squares, measuring tools. Wooden maul, straight chisels for cutting slots and skiving if need be. you can also make some of your stuff if you like, edge burnishers or a slicker for example and your stitching pony. You will also need some punches and maybe a rivet setting tool. Will you want to learn to tool or stamp your leather or just make plain stuff to start? I use a head knife or round knife very seldom. most of my cutting is done with a knife i made that can also be used for skiving, it kind of resembles a Japanese kiradashi knife. you will need a good stitching awl and a wine cork to go with it.