Don't use internet forms to create your entity.

Has anyone had better luck with one material or another flooring over a basement?  

If you are trying to cut corners on materials & finishes, skipping code requirements and generally hacking a house to squeeze out profit...my advice is to invest in the stock market and not real estate.I personally have seen downtown high rise condos literally double in value after rehab largely because many are decked out like its 1985.

Question:   Since we did a considerable amount of sweat labor ourselves and spent quite a bit on appliances, paint, flooring, plumbing, electrical, materials, and contractor labor and materials, do I need to write up an itemized list of the labor and materials and give it to them, or just write a list of the things that has been done?

You should be paying sales tax at the point of purchase for all materials on your rehabs...if you're pulling permits to do the work, most jurisdictions will ask you to put up a use tax bond for the work.  

who's going to track materials and labor costs for you? 

very simply put its a beginners game.. and beginners are beginners they simply are not educated enough in real estate to be dealing in these transactions... so its really the blind leading the blindand not sure where you think all these sellers need help from unlicensed rookies... granted everyone has to start somewhere .. but this wholesaling because of what goes on on the internet is just over run with begineers and those who simply are not ready for prime time.they are learning their craft from ceral box  is all they are doing..

TV, WiFi, Internet are as important as the Microwave.

As a wholesaler in Washington I am concerned about a Seller who may not fully disclose material defects that affect the value of the home. 

One guy told us $4,000 if we supplied the materials, but he bailed on vacation and left us hanging.