I apologize in advance for the detailed post

We are trying to finalize our budget and take into account an estimate for tipping our vendors. We have the following vendors-
DJ- we will have 2 DJ's, 1 is the owner of the DJ company. The DJ company is also providing the uplighting and dance floor lighting for the reception. Should we tip both DJ's, even though one of them owns the company? Should we tip based on the total bill (including lighting) or just on the service portion?
Photog- again we will have 2 photographers, 1 is the owner of the studio and she will have an assistant. Should we tip both? And if so, should we wait until the proofs are in and the final payment is due? if that is the case, would you tip the assistant on the day of?
Waiters- We will be having a buffet and our contract inclues 1 waiter for every 4 tables. The contract price includes a service charge. Do you still tip them? If so, do you tip every waiter individually or a total amount to the "head" waiter (assuming there is one)? How do you recommend calculating the amount per waiter?
Bar Tender- The contract price includes a service charge- do you still tip? And how do you recommend calculating the amount?
Venue Coordinator- The contract is inclusive of service of service charge- do you still tip?
Any advice that you have would be helpful. Thanks!