Couple questions on a Robberg Express

I've never seen one of these Robberg Express surfskies. (Tampa, Fl). Anyway a really beat up one is on the work table. I have a couple questions as I start down this rabbit hole.

1. These are single hull meaning no foam core? Yes? no?

2. Preferred glue to repair the seam.

3. on the stern there is what appears to be a hole that someone glassed over. Was this the main drain plug at one time? The only other hole is at the upper right of the footwell but I think that was only for a bleeder tube.

4. In the footwell there are two sets of pad eyes. Is the bottom on for the rudder assembly and the top a bungie? The previous owner was using the top for the rudder lines.

5. I cannot find any ID on this boat where do they write the number. I am used to finding them on the stern.

6. Is replacing the SS rudder lines and tubes with Amsteel/Dynema a wise decision?

7. The previous dude tried to gelcoat it. The white was goop that I am trying to remove. The blue I am sanding down to the orange but appears to have cured properly. Must I remove it all for a new spray coat of gelcoat?

8. The ski had a grey bow and stern and the upper hull was orange. The lower hull white. Was that a typical paint scheme?