Some of the knobs come with multiple inserts and scales, so they will work on different brands and models. 

Insert a third party to ensure that it is an arms length transaction.

Keep in mind for a flip, the profit isn't treated as capital gains (insert all the typical disclaimers as I'm not a CPA, check with yours), but generally as ordinary income - including payroll taxes, etc. 

Perhaps you should seriously consider searching out a local person that has cash to insert, but no time, flipping experience or desire to oversee contractors and the entire process of the flip project.

Then read your counties rules on the process and then search google for “buy (insert county) tax liens” You should also check to see if your county holds tax deed auctions this will jump you ahead of the tax lien process cutting out a lot of wasted waiting time 

Do NOT go the cheapest insert.

The contract will discuss payment terms in addition to 'scope of work' (be as detailed as possible - you CAN insert their bid sheet if it is detailed enough, or you can add a page with more details) and timeline for completion of 'milestones' which can be used for disbursement of funds. 

I added a gas fireplace insert in an existing wood burning fireplace when the original chimney was damaged in an earthquake.

Take "Only Section 8" and replace it with "Only African Americans", "Only Christians", "Only (insert protected class)".

All this is documented.I may be wrong (gotta insert a standard "ask a lawyer" in here somewhere.. so definitely ask one), but I think the chance that the government would ever pick a complaint from this guy as the hill they want to die on is about zero.