What's a good rod length and action for top water fishing? Is 7.1:1 ratio good for top water fishing?

Length is very subjective. I personally like b/w a 6' and 6'6" rod. The action should be fast at the minimum. A 7.x:1 reel may be fine; however I find that when walking a dog, frog, or chug bug, I really prefer a 6.x:1 reel.

Depends ...If standing on the deck of a bass boat then a 7 ft. rod could work - all around I believe a 6'6" ft. to 6' ft. is better and a 6:3:1 reel speed is fine for poppers , twitch baits and walk-the-dog spooks   . I believe you only need a 7:1 reel if you are using your rod with big sweeps to move line (jig , carolina rig) and need to catch up to a fish quickly for a hookset .

Your reel is fine. I suggest 6 1/2' - 7', whichever you prefer.

If you go with a MF rod it should have a soft tip. An example

is the Avid AVC66MF. This is my dedicated jerkbait rod. This

would make a fine topwater rod, too!

Most times when I'm "working" a lure I'm doing it with wrist and forearm movements, the reel just takes in the slack.  IMO if one is concerned about gear ratio then the movements are too fast, bass love to hit topwater when the lure is "at rest". I use any where from a 6'6 rod to an 8' rod to work top water baits.  The longer rod does take some time getting used to and could lead to fatigue and soreness at first.

I use a 7'3 rod for walking baits, I use as fast a reel as I can get, not to work the bait but to catch up to a 4-6 lb spotted bass once it does eat.

For spooks and poppers, I use an Avid 6-2 M-XF rod. Reel is an Alphas, which is around 24IPT.