Looking at the couple hundred or so negs I made with my 8x10 in the last 18 months, the best ones were made with a 240 (a little on the wide side), from a distance that yielded a waist-up shot. I usually shot at around f16 at 1/8th or 1/15th on fast (250 to 400 EI) film, and didn't have issues with focus or movement. Times when I used my 360, I had more focus issues.
My best advice is to start and stick with one camera, one lens, one film, one developer, and work on the connection with the subject and the light. I wasted so much time jumping around with lenses, films, and the rest, when it's really all about subject and light.
All that being said, for my own work, I discovered that while I do get a certain appealing "look" with 8x10 and I enjoy having those big negs to make Palladium prints with, I ultimately do better portraiture (connection with the subject, composition, handling the light) with smaller formats. I will probably sell all my 8x10 gear in the coming months for this reason. And, in my experience, it took the best part of a year to get really comfortable with all aspects of the process and to stop making stupid mistakes. Practice made perfect, and also made for a lot of wasted film and missed opportunities.
For one project, you might consider trying to borrow a camera and lens, or maybe rent one, rather than investing money (and lots of time) assembling a kit of your own. See if you like it before a big investment?