I gotta be able to live whilst building the nest to inject into investments. 

Do them a favor and inject a little reality into their dreams of market domination.

They can either tent the house, or "spot" treat, which is injecting chemical into the walls wherever they see signs of them.

When calculating that, do you go off the purchase price, the purchase price plus estimated closing costs, or the mortgage amount after equity injection?

Where did that increase come from, not from the property, from the cash injected.

The money is deposited into your business account and on your balance sheet this would be considered a "cash injection" to the company. 

Then, when it's time for them to inject the capital, they develop a case of alligator arms and they struggle to reach their check book.

Nicer houses I fix and flip.YUP prepping these documents is super simple.. the legal descriptions dont change its just copy and paste from the last recorded deed and inject the sellers name as the person or entity on title and the buyer whatever entity you want to buy in.in my foreclosure rescue days ( when it was legal in OR and WA ) ALL of our deals were done within 48 hours of the foreclosure sale ( seller most motivated and no competition from those who dont know how to do these deals this way which is 99% of investors)  We typed our own Deeds got the seller to a notary or mobile Notary had my secretary run the deed to the court house and record it  DONE.. in the mean time i had a courier service running the Cashiers check to redeem the property to the foreclosure attorney DONE.. knowing how to do your own title and escrow is were the money is for those who want to take just a little more effort and not think they need attornies and escrow companies to do real estate transactions. 

Many people find that they are already good at something and use that income to inject into the deals of others... 

The bottom line though is you'll likely need more equity capital injected into the project to make the deals in this day and age cash flow positively.