After you get out and use your boat on a river you may be able to answer the questions for yourself based on how the boat rides. Using fins in anything but the slowest current is a bad idea. It would only take one submerged log to pull you down. I think trying to pull plugs out of a small pontoon boat is more trouble than it's worth anyway.
You can use the motor on lakes if you can afford the weight. I weigh 225 and my Southfork sits low enough as it is with just me.
See how the boat feels to you and then think about it.