As an bus/motorhome conversion, it is generally treated the same as an RV. A CDL is not necessary even with air brakes. You should check with the DMV and your insurer in your own state. Rules vary widely between states for this type of vehicle. Avoid telling the DMV and insurers that you intend to live in the vehicle if possible. I didn't say lie, I said avoid giving certain information to make your insurance experience smoother.
The majority of us here are on tight budgets, and a build can be done relatively inexpensively. It depends very much on what your vision of the end product is for you bus.
There is a great deal of information about solar here, and experienced bus owners with solar systems.
Many people tow a vehicle or trailer with their bus. Some of us with wheelchair lifts have a garage in the bus for motorcycles.
Where we park varies as much as the people driving the buses. National forests are popular for boondocking, but everybody has to go shopping and do laundry sometime. Some people are actually traveling. Others have negotiated a more permanent place to park. It all depends on what you're wanting to do with your bus. Just like building it. I like the idea of getting insulation in the ceilings and walls first so you can make a heated area during the winter. Others roam where the temperatures are more comfortable and don't feel the need for the same type of build. That's to broad of a question to answer.
Are you finding anything similar to what you want in your end of the country?
where do you all park your homes?