Before you do anything get the value from NADA and have the motor checked by anyone you trust other than the car dealer.
a few of the main things to look for IMHO is to bounce the motor and check for any movement on the transom, look under the boat for cracks or exposed fiberglass. Open all the boxes looking for standing water, cracks or pealing fiberglass. Make sure all the switches work, lights work, live wells work and hold water so you know what you need to fix on top of the price you all agree on.
You said there is a good scrape on the front? if there is exposed fiberglass that could be a big issue depending on how much if any has made it's way in to the rest of the fiberglass in and around the scrape.
As far as a cover all depends on what you need it for. If you are going to keep it covered while parked most anyone from Wal-Mart or BPS will be fine but you will need to open it up a good bit to make sure it doesn't start to mold under it in the heat. If you want one to travle with they are going to run a lot more$$$$$.
Good Luck,,,, two things to keep in mind is that the bests days to own a boat are the day you buy it and the day you sell it,,,, the 2nd thing is BOAT stands for Break Out Another Thousand.
See You On the Water
Fogy