Noob question hull cap separation?

[ashokrags]

Hello
I am concerned that I might have a hull so separation issue. Why I think this is because of two reasons
1) boat started listing a little to the starboard side. We couldn’t find any obvious water build up
2) recently was seeing some rust dripping out from the under rub rails and I could see that there were some locations where the caulk had come off

Some questions I have are :
1) Any insight as to how I would determine if this is the issue without removal of rub rails etc or is that just not possible?
2) How much time would it take to try and fix myself ? Any estimates would be great.
3) if I were to have it done by a shop what would I be expecting to pay for the same.

Any and all help will be appreciated. I will post some pics sometime next week once my boat is back from spring tune up.
Cheers
Ashok