I was able to solve #3... but 1 and 2 are another matter.
For number one, you have to eventually solve in your proof for D --> A in order to use Modus Tollens with line 2 (~A) to get ~D. That much is clear.But what is evading me is how to get A --> (B v C) and Modus Ponens to get D --> A. The only possible way I can think of solving this problem is with sub-structured nested proofs which I don't know if your allowed to use.
So the end of # 1 should look like this
#? - D --> A Modus Ponens ???
#? - ~D Modus Tollens 2, ???
For number two... that is a dill of a problem. Besides an indirect proof " A- AP" or conditional proof, the only two ways to kick off the proof are by transposition "~B v ~A" or implication "~A v B". The rest is nerve racking without complex nested proofs, and even then I'm not quite sure.
Sorry about that, I wish I could be more helpful. If you have any questions on the two I solved or want to try to troubleshoot the other two, let me know.