First of all -- where in MN are you? I ride the St. Croix River in Hudson but work in the cities.

For the exhaust you'll want to pull the center bolt and take the supertrapp and all the plates off. This will leave a flange at the hull. Remove the flange and then clean all of the old sealant material off of the transom. I'd also fill the holes with some kind of epoxy (marine-tex, JB water weld or ???) so that you can redrill new holes for the screws to mount the flange. Then you want to use either black permatex or 3M 4200 to seal the exhaust flange to the hull (and also to the inside of the exhaust pipe) . Make sure to put a dab of this on each of the screws, too. It's an hour job if you bust out a wire wheel to clean the hull. (Be careful!)

You can do the same basic thing with the wake-plate. Remove, fill the holes, inspect for cracks, and then reseal.

If a hose filling the inside is causing the leak, it's pretty significant and I'd address it before you use the boat again. Small leaks will require the weight of the boat to provide pressure for the water to enter.

You can check your stringers by inspecting the motor and transmission mounts. They should be solid and not easy to turn. Don't get too crazy and strip them out -- if you can't turn them easily, you're good. If they turn a little bit or don't "bite" into good wood, you can try to use a longer bolt (galvanized) or go one size larger. If a longer/larger bolt won't bite then, and I hate to be the guy with bad news here, you have real problems. We're here to help but you won't like what you hear.

And it might not seem major but I ignored my stringer problems and tried to wish them away and my boat sank. I don't think anyone else here has quite as dramatic of a story but it is a serious issue. Let us know what you find!