I have been doing leatherwork for 35 years, and I design just about everything from scratch --- I rarely use patterns, as I love to design different products that fit my image of what they should look like. I also hand select all my leather, or my partner does that I have trained, because I know what I want leather to look like, feel like (hand), and smell like, yes that can make a difference...
As far as being an expert, I have been called an "Expert" and "A true craftsman" by customers, and other leatherworkers, but I have never described myself as such.
Having a shop is nice, I have two --- one in my "man Cave" and a real shop behind my house, but I have seen some guys produce some pretty amazing leatherwork from basements, or just a corner of a room in their houses.
I was lucky enough to apprentice under an old biker that specialized in the Motorcycle genre of leatherworking, that experience was invaluable --- of course it was before the Internet and google...
Tools are a whole different animal, if you do some searching on here you will get 100 different opinions about which tools are necessary, and which tools are the best. If you spend the money and get some good quality tools at the beginning, it will make things easier for you. I have some Barry King tools, C.S. Osborne, Weaver Master tools, and a couple of Tandy tools that pale in comparison to the others I mentioned. If you contact one of the reputable tool makers they will be happy to discuss what tools are best for the type of leather work you are interested in...
As for sewing machines, I have two Singer treadles that are almost 100 years old that I use everyday, In addition I have a Consew 227 R-2 that I think is a great versatile machine --- it will sew everything from 46 to 207 thread with absolutely no issues.
Good Luck, and continue to study the wealth of knowledge on this site, and pick the brains of some of the members --- there are some really great leather craftsmen/Artists on here who are always willing to help.
'