Either will suit you well. For the open ocean, the Adventure is recommended over the Revo mostly because its just a bit faster (longer range) and argueably handles chop a bit better (but wetter). Can't go wrong with either though. Revo is prob most popular for any kind of fishing situation.
1. Its all relative. They are pretty fast compared to other fishing style SOT kayaks. They aren't going to beat out a fiberglass hull slim 16' all the time but those yaks are built for a different purpose usually. It really all depends on you as a paddler. Personally, I am much faster pedaling an Adventure than paddling it. I don't have all the proper stroke techniques etc (this is my first yak), but if you are an experienced paddler, you may find other yaks slightly faster.
2. Adventure paddles better than Revo due to smaller width and longer length. It tracks better too as the Revo must have the rudder down to avoid going all over the place. I can't intelligently compare them to other yaks but I have both an Adventure and Revo so I know the differences in those two.
3. I only fish 'flat water', ie smallish lakes and streams where chop rarely is higher than 1 ft. To me, the Adventure seems just as stable as the Revo. In rougher water, I do not know. They are both quite stable though. You can hang your feet off of the side and fish. I can do hard hooksets across the bow and never feel unstable at all. As a current kayaker, I do not think you would feel tippy in the Adventure. Its only uneasy for the first few times (as with any new yak) and then you are used to it and totally comfortable.
4. Wrong units pal.

No one seems to have much trouble. The pedals have 7 different settings and the seat has two settings. I'm 6'2" and fit fine and even kids can get in and set it up so they can reach the pedals. You should not have a problem in either yak.