(1) Bus service at the Epcot resorts has been a problem for some time. If in fact the routes have been permanently split, the situation will probably have improved. Give it a try if you're so inclined. It's the simplest alternative. Remember that in a pinch you could take a bus back to any of the Epcot resorts -- it's a short walk.
(2) The advantage of driving is that you control your time of departure. If it's important to you to arrive before park opening, driving gives you that control. MK at park opening is also when the bus system is strained to capacity. Driving is not necessarily slower than the bus; it can actually be faster if you consider the time spent waiting for the bus.
(3) This is an adventure. If you like hiking and you're not looking for the fastest method, go for it! The Epcot monorail should not be missed. You can catch the bus on the way back if you want.
(4) I can't think of any good reason for using this approach.