Nice to know that we have the same field. I’m into auto parts/spareparts business. At first it was starter on my community with small capital of $500 for the supplies. I’m just renting space and i must say that i got a good place. It was in the middle of school and market which a lot of passers by. With your question.
1. Japan model are quite expensive but it is very click to the market. On my case like what i’ve said i just start $500 but that was few years ago. Minimal stock of supplies and those everyday supplies are my target such as tire, knots etc. ITry to check which is the most sellable on your place so that you would know or you will got an idea with your target.
2. You can start even a small place, you can rent or build your own. A room type of space is good enough for the beginner. Like on my case,I only have a minimum capital so expected that minimum supplies i can sell, so if i will going to rent a very big space for minimum supplies it doesn’t make any sense right? If you have a big capital for supplies then its good to go for a big spaces. One tip i can give with regarsd to place, check the background history and look for a place tht very accessible in the market as well as electricity/water supply. Those are the primarily thing that need to consider when putting up a business.
3. If you have a lot of knowledge and know for your self that you can handle it then that’s good to go, hiring another mechanic wil increase your budget snce your just starting up. But on my part i hired one mechanic because when i enter this business i only have few knowledge bout it.
Hope those tips help you. Good luck and welcome to the community.