I have just finished a 203k loan on a triplex (242k purchase price 180k in renovations) It was a pain in the butt and took a long time to complete but it was well worth it. We did a full 203k loan, it took us 6months to close on the house due to sellers and the red tape that had to be navigated for the loan. Then another 3.5 in renovations. The long version is for another time.
I would recommend doing a 203k streamline loan. It has a cap of 35k and doesn't have near as much red tape.
To start off you need to get a 203k hud consultant to do a minimum property standards inspection. As far as a full 203k you are not allowed to do any of the work yourself, your contractors have to be licensed, bonded and insured. All their information needs to be submitted to the hud consultant and to the bank. Once you have your final rehab number you are going to have to submit a detailed scope of work to the hud consultant and the bank. The bank is going to look at the work that is going to be completed and then require a percentage over the estimate for a contingency fund. If you have money left over at the end you are allowed to submit a change order requesting the remaining funds be used for something else.
During the renovation when a percentage of the work is completed you will have the hud consultant come out and evaluate a portion of the work was completed. After the inspection you submit to him how much you want to be reimbursed for, that will go to the bank and the bank will cut you and the contractor a check (third party check). The bank holds back 10% from every draw until the final inspection then all funds are released.
I hope this sheds some light on the 203k. If you have any specific questions I'd be more than happy to answer them