I recently bought Wilton's pillow pan set and before I try it out I want a bit of advice.

1) When stacking them do I need to put a thin cake board and supports between the 2 halves of the pillow?

2) Do I need to put a central dowel down the middle of all 3 pillows once stacked and if so how is the best way to do this?

3) Is it best to cover both halves with fondant and then assemble the pillow or should I cover the bottom half, turn it over, place the uncovered or covered ???? top half and then cover with fondant?

4) I really need it to be stable for transport. Should I transprt it unassembled or is it going to be okay fully stacked over some rough roads?

Any and all advice will be welcomed. Please help a sister out!!!! Thanks.

I don't think you need a board and support between the two halves, but you will need it between the pillows, especially on the bottom one.
For the covering I would go with the rotating system, covering first the bottom half, so if in turning it you get any scratches it won't matter as much. Try freezing the cake (15-30') before the covering.
I don't know how long the trip would be, but since it's such an easy cake to assemble I would bring the tiers separately and finish once you're there. This way you will be sure it gets there safe!
For the central dowel, if you assemble it on location, you really don't need it, if otherwise you decide to bring it already stacked, well then it will be necessary!