Telescope Reviews: Reviving an old observatory or start over?

I have a roll off roof observatory that has a number of problems and I'm trying to figure out whether I'm better off fixing what I have or tearing it down and starting over. Obviously I would prefer not to do that. The observatory is 12x10. I will be using it with my 20" Dob or my other telescopes. It was built originally with the Dob in mind.

Problem 1: Dirt floor. For this app, do you think I need to poor a floor, or can I just use patio stones? I could either do the entire floor or leave where the rocker box sits bare dirt.

Problem 2: The roof rolls off to the North. The door into the shed is to the South. Because I wanted a low south view, I built one half of the wall up only half way. I can then open up the wall on that side. Between that and the door, if I time things right I can get a view pretty far South. The problem is that because of that, the two side walls are not tied together at all on the South end. The result is predictable, the outside walls want to shift out. One possible solution is a wire cable with a turnbuckle between the two sides.

Problem 3 - My door was just double layer plywood with some hinges. a) the hinges are not heavy duty enough. b) the door is totally falling apart. c) The wall it hinges to shifts somewhat, again because there is no cap plate, etc. The door is quite wide and needs to be to get the 20" in and out (4 feet wide). I'm thinking about again building one out of plywood, but this time using 1x1s inside and then skinning it with the plywood.

4) I get water in the observatory because of gaps between the roof and the walls on all sides. I think I can fix the gaps on the side by going up with 1x8's or something from the top of the outside bottom section. On the North side, I can probably go down with a 1x8 secured to the 2x4s that make up the bottom frame of the roof. But I'm at a loss what to do with the South side with the door.

5) I used wavy steel roof sheeting (whatever they call that stuff) for the roof. Unfortunately although I capped it with the piece they sold, and I used the waffle boards for it to lay on, on the side, those waffle boards did not hold up to exterior weather well and have fallen apart. This leads to gaps between the cap and the roofing, again which leak.

I'm thinking of pulling the roof on that side and putting down strips of 1x4 or 1x3 which I used on the other side and which have held up much better. While doing that, I have the obvious option to replace the roof material entirely. Any suggestions one way or the other.

Obviously I would rather not start over if I can avoid it. The roof DOES work and I remember what a pain making it in the first place was.

Thanks for any suggestions.