Some comments on Peter's replies:
The mickey mouse repair problem is obvious. It's hard to judge from just the pictures, but removing the caulking might show you that the underlying problem isn't really all that bad, if approached with the right fix and correct materials (fiberglass).
The transom seems to be the weak spot for this boat, but it would not be the first DS1 with that issue (as you can read here in the older posts). I'm afraid I missed the significance of the plywood reinforcements for the gudgeons - they were visible on the original photos by the previous owner, but on the closeups it's clear that Peter called it right: a strong transom would not need them.
The caulking at the bottom of the transom is to cover a removed or leaking drain hole. These boats us usually have a 1" brass drain with a rubber plug at that location.
On the bow area, I disagree with Peter. On the older DS1s you can get a depression between deck and rubrail. Some of what looks like cracks on the photos (i.e. 5 of 15) might in fact be caulking that's flaking off. That can be removed. If there's a need to seal the deck / hull joint, in my view, the better method is to glass this over from the inside.
On the starboard side, it appears as if the deck is cracked where it meets the hull. Again, adding a layer or two of glass from the inside between deck and hull would initially seal the area and provide back some the strength lost. That would allow you later to replace the rubrail, and while the old one is off, and before the new one is on, to grind off, and rebuild the broken fiberglass.
I mentioned the possibility of staging repairs. Do the minimal, safety and structural stuff first, put her in the water and sail some, then do the next stage. Fixing the deck/hull joint by reinforcing it from the inside is a phase 1, doing the rubrail/crack fix on the top, is phase 2, painting/surface is phase 3 (or phase last

)
The good thing about the DS1 is that, except for the flotation tanks there are no hidden places for water to accumulate (no double hulls). The photos from the original listing show it floating, btw. If those are recent, I wouldn't expect a leaking hull. (Possibly a slow leak at the CB handle).