The good news is that at least half of your questions have been answered here before, and you're just a keyword search away from them.
4x4: rarely done. Expensive, crazy expensive, and not needed in 90% of situations. For the cost buy a used SUV?
Shuttle bus v Short Skoolie: if you plan to 'offroad', lean towards the skoolie since Shuttle buses have very little clearance.
Welcome to the forum-looking forward to your journey and learnings.