This is technically a method of buying/selling real estate, which is illegal without a real estate or law license. 

2.For purchases made on a credit card, is it best to use separate cards, or are there good methods for tracking expenses by property?

If you are seen to be using this for investments, then you will find it hard to get another FHA loan, making this method difficult to scale, but good when you are getting started.

All I’m doing is educating and sharing my methods, for free.

Nathan's search method usually works, but I use what Google suggests: '<search item> site:www.biggerpockets.com' (without the single quotes on the Google search bar.) 

It's a method of getting them to participate so they feel comfortable asking questions and learning.

Our city code requires a method of egress for 3rd Floor units.

Also, is there any method you know of to shorten the cash cycle?

I renovate 50+ houses/year through the BRRRR / Flip methods and also help dozens of agents do the same.

Have your attorney send your contractor a letter explaining your dissatisfaction, any legal, ethical, or moral violations his operating methods result in, and making him an offer BELOW your “target” amountbest of luck I have an attorney that I considered speaking with on this matter, but I’m not sure that he specializes in things like this.