Need to buy a topwater rod. I want a MH power for walking treble baits and although fast action rods are the norm for topwater rods wouldn't a MF action fit the bill better? It would allow the fish to swallow the bait better, plus if I acted too fast in setting the hook out of excitement this would give it somewhat of a delay from pulling the lure out of his mouth correct?

A fast or even XF tip is faster to recover and gives you more control when walking a bait. The difference in hookset speed will be marginal at best. Just make sure not to set the hook until you feel the fish (I usually reel into fish on walking baits before I sweep set into them). 

I do. I don't feel a mf has that much effect on walking the bait, at least on a stout rod, and help give you more distance on the cast as well as more forgiveness for trebles. Once you feel the weight of the fish you can really lay into it and pin the hooks well with a lower chance of ripping the bait away.

Would medium heavy with a fast tip be to much over kill

I use a fury 703c great walking bait rod up to about 3/4oz

I use the Daiwa Tatula Elite 7'2" MH with their "regular" action which is really a mod fast. It has been awesome so far as my top water rod. The tip is still plenty fast enough to walk baits without an issue, and I have had no issues keeping fish pinned on treble hooked baits.