re: Please help direct me on business set up

First I would look at organizing versus staying sole proprietor. For liability purposes most people will organize/incorporate. If you organize/incorporate you will then have to decide how the org/biz will be taxed. That's a CPA question. The answer to that Q will determine whether you need a Tax ID.

I would say you need some liability insurance. If you fix Mr. Smith's computer and somehow erase some proprietary data he may want to sue you.

Read up on business plans and get at least a very scaled down simple one in place.