There is a small hole under the rudder bar. Do not close the hole. It is there to help the hull breathe. Also, a lot of moisture can collect in all the hulls so keep them aired-out to keep 'em dry. Osmosis is a killer.

That looks better.

It would help to remove the plate and reach inside to glass the inside of the seam for reinforcement.

A replacement for the plate gaskets is 1/16" Yale Cordage Pulse Racing Braid. Any 1/16" braid would do. I think it's Yale's Aracom Miniline which is overkill for a gasket but I had some lying around and it works. Take those plates off after every outing to allow the inside to dry. Even high humidity can cause water collection in there.

As my boat, #152 in 2012, has aged and oxidized despite waxing, I have the same repaired look on my port side on the rudder support as yours. The starboard side is showing a couple of hairline cracks. I can tell it's been reinforced underneath more than likely at the factory before it was shipped. I will have to tend to the cracks. Usually, the preventive fix looks worse than the original problem. I take photos just in case I sell it in the future. The second generation boats have a better solution back there.

Wow. It looks like it may have fallen to the road while being trailered. First, if you are not familiar with glassing and gelcoat this is going to be a tough one. That ama has been hit and there may be more structural damage than is visible from the outside. Remove the deck plate and take a look inside. The plate is often in their very tight, so you may have to use the ends of some pliers to lever it counterclockwise. Take a look at the ring gasket if it still has one. Renew both on starboard and port. The deck plate outer ring screw was tightened too much and cracked the ring, so the ring needs replacing. Those plates and rings are hard to find in the aftermarket. They are an odd size. A Weta dealer should have spares. I've never had to ask.

The gelcoat is probably delaminating in more places than the obvious one in the photo. If you see a lot of hairline cracks on the hull ready to open that's bad. Push with your finger on the cracks to see if it breaks. If it's that far gone around the hull I wouldn't spend the bucks to renew the hull because this hull may be delaminating and blistered where you cannot see it.

The stern is repairable but that is an indication of the condition of the rest of the boat and how well it was not taken care of. The photo of the stern shows a past fix on the rudder support. The hull is not meant to be pulled or pushed there. It is tempting to grab, but it will break as this one has. It is an obvious weak point of the Chinese built boats. At best, this one was cracked badly enough to have been repaired as shown by the lighter oxidation color.

On the bow is that carbon fiber or a carbon fiber lookalike with epoxy?

Get an estimate from a reputable repair shop. Unless you know someone to guide you while do-it-yourself I would buy a new hull. Maybe someone else can jump in with better, cheaper, and more hopeful advice.