Welcome to the Supra world.
As others have stated, first take a deep breath. I know it seems real crappy right now, you feel taken advantage of, and are probably having serious buyers remorse. But all of the issues you have noted can be fixed. Some easy, some not so much. But there are ways to work with it.
Lets start with the easy ones first. The blower and the bilge. Mine only had one blower running as well when I got it. It turned out to be a bad wiring problem. Are you any good with electrical wiring on say a car? If so, it's the same concept, check your power and ground at the blower, and then trace it back. Your blowers are under the rear hatch. You then remove the screws that are holding the storage bin in place. Once you remove that, you will see your two blowers back there.
Bilge pump. First off, I'm a safety nut. My family rides in my boat, so there are no second chances if something happens. Any boat I buy, gets a new bilge pump. I don't know what the old one has been through. Bad wiring, did they ever leave it on for long periods of time, was it full of gunk, etc. Get a new large bilge pump, that you wire in personally. That way you know it's good, and a new pump. My guess is the check valve on yours is worn out keeping it from fulling pumping all the water out.
Carb. Have you ever done any carb work? It's not too bad once you do it once. But lets start with some simple diagnostics first. Get yourself a 5 gallon can of fuel, and about 4 ft of fuel line from an auto parts store. It's always handy to have around anyways. Then run the fuel line straight into the fuel pump on the front of the engine. Trace the hard fuel line from the carb down, it will go into the pump. On the pump will be a rubber hose from your gas tank. Put your new line to the 5 gallon can there. Start your engine. Does it still sputter? If so, it could be the carb or the fuel pump. If not, and it's better, it's probably just the fuel filter. Next, disconnect the fuel line from the carb and turn the motor over. You should get a lot of fuel out of the fuel pump. It can still be bad even if it's pumping a lot, so that doesn't rule it out.
Next, there is a tiny metal screen right where you disconnected the fuel line from the carb. Check it and make sure it's clean and free of debris. That can affect the fuel flow. If these all check out, then your carb probably just needs a good rebuild. We can walk you through that as well.
As for the stringers. Well the reality is, most all of these boats that are pre-1992 are going to get stringer rot at some point. It's only a matter of when. The bad thing is, it sounds like the seller knew the stringers were bad by putting epoxy in there. That is a band aid that I have seen work, but normally only for a season. I know guys that have run their Supra for a year or two with stringer rot, but they are gambling big time. If it turns loose you are screwed big time. Pull your lag bolts out, and check them out like others have said. You can try to add some diameter to them and about 1/2 an inch in length to see if they bite and hold. I've also seen guys over-tighten them and strip them out, and then you think the wood is bad. But in reality the wood was fine, and a larger bolt held for years.
Take pictures, that helps us help you a ton. Take a lot of pictures of what you are working on, problems, etc. And then we can visualize and assist. Plus we just love to see the new Supra's in the neighborhood.
Again, don't worry. You've got a Saltare, and many of us have them here, so you're in good company for help.