The purchase and sale agreements the assignment of contracts, you know the vital legal instruments needed in the transaction of real estate.

"Mortgage" is the security instrument used in ALL those loan transactions.  

As for expenses, given their volume of transactions over the years and track record (and again happy investors), I doubt their have been significant fluctuations which have caused any material changes to their estimates.  

Fingers crossed.

@Fantasia BowserYou have been given the proper answer, but on a side note, as it appears you may not be entirely familiar with basic contract law, you may be lacking some critical knowledge in other investing areas too so it would be wise to consider partnering on your first 5 or 6 deals with an active local investor so you can learn how to properly enter and exit a transaction without causing yourself potentially serious ramifications. 

Should we have an LLC in order to facilitate the initial transaction of getting the property under contract?

Fellow BP Investors,I'm trying lock down accurate numbers on the buy / selling transaction costs associated on a flip.  

You can also hear how individuals transitioned into big transaction such as flips and buys n holds. 

Very above board and clear transactions. 

One thing that I don't think was brought up is fair market rent and arms length transactions.