It is virtually impossible for anyone on this forum to give you specific advice on your case without intimate knowledge of your claim and damages. And this required knowledge is far beyond the capabilities of this forum. For example, we don't have any information on any contracts you might have entered, or any specifications, or even the actual work that you had done.
Nonetheless, here is a VERY generic response to your
questions:
Q1) "How do I figure the FINAL DOLLAR amount of my case?"
A1) You will need to determine the REAL amount necessary to 'make you whole', as if the damage were never done.
Q2) "Who My witnesses be?"
A2) Besides the question of grammar, no one can answer this. If you can make your case without witnesses, then you don't need any. If you feel that your case needs witnesses to substantiate or support your claims or losses, then you will however many are needed.
Q3) "I have pictures of all the complaint areas. Estimates to repair. What else do I need?"
A3) You will need whatever is needed to support your claim of damages and the amount of those damages.