Cool. Sounds like where I started this summer.
As for the exposed fiberglass on the corner, I recommend you repair that to keep water out. Fiberglass resin or some sort of hull repair kit should do the trick depending on the size of the damage. I would take it by a few marine repair shops and get some input from the pros. Always good to seek advise from those who do the work daily.
Wet sanding is a lot of work but as you can see from my photos, it's worth the effort. I've been told that the aging of the gelcoat will return to it's faded hazy color within a year but I've kept mine covered all summer and I use polish about every 3-4 times on the water which helps maintain all of the wetsanding and polishing I did.
Mine has snow over the tarp too. I bought an inexpensive universal boat cover from Walmart (about $40) because there is no cover available that is specifically designed for that boat due to it's age. I'm using a heavy duty contractor grade tarp for the winter months. Works great but it keeps moisture in and makes the boat sweat. I have to air the boat out every few weeks when the sun is out for a few days.
The windshields on mine are the factory originals and you cannot replace them unless you have them custom made. There is a place online that sells replacements. I'm sure you could Google and find a place that is willing to make replacements if you sent them your originals. For a large fee I'm sure.
I'm the third owner of my boat. The first had the boat for a few years and wanted a ski boat, not a fish/ski combo. The second owner was my cousin's family and they used it mainly for a family ski boat. The kids are all grown and out of the house so the boat was no longer needed. It has the factory original 85hp Evinrude and I've had a compression test done this summer which showed very high compression. Great for a 30yr old motor. In a few months I'll get a tune-up and new prop. The new prop should push the little boat up to 45mph (GPS) which is really fast for an old tri-hull.
My deck was replaced about 5 years ago. I recommend you have someone do this for you unless you are willing to dig in and do it yourself. It's a lot of work for a novice. My deck was replaced with marine grade plywood and then cased-in with fiberglass laid over the plywood to seal it permanently. The guy who did it was a perfectionist and over-acheiver to say the least.
I hope to get the boat out a little this weekend. I'll try to get the pictures and measurements uploaded this weekend. I need to get it out anyway.
For marine carpet, you can get that locally or over the internet. It's fairly reasonable. Just about any marine dealer can order it if they do not already have it. Bass Pro Shops has it, Cabelas, etc. There's tons of places online. Possibly some of this boards sponsors.
Again, good luck with the restoration. It's fun and the rewards are worth it. Enjoy the boat too! Spring weather is only 3-4 months away!