Funds from a refi are not taxable.  

Is the $20,000 the taxable gain or total cash you should recieve after the sale?

Your gain will be fully taxable but because you receive the money in 2017 the tax will not be due until April of 2018 thus extending use of the tax for your benefit by a year.

I have taken properties that are the ugliest on the block, with no one living in them, and increased its taxable value by 3-4 times.

Service Tax Registration:- It is required for any business that provides more than 9 lakhs of taxable services in a financial year.VAT Registration:- VAT registration is required for any business that sells goods and products.

And do the rules for what the business/ employee can contribute base calculations on total income, gross profits, AGI, or taxable income?

@Carlos Rovira the general rule is that income is taxable in the state in which it is earned.

You may want to consider a strategy such as Cost Segregation to help lower your taxable income and maximize current year deductions to generate a loss that will carry over.Third, You NEVER want to hold rentals in a corporation.  

. $200 lot rent and $300 payment towards the $3700.Lot 17 Park owned but renter might by it on payments $200 lot rent and $300 =$500Land taxable value is $72910.00 and Building and homes owned by the park is $38610.00 per county records.Total property taxes including the homes is $3558.00Liability Insurance  $714.00 / yrMobile Home Ins

If you are looking to lower your taxable income, this could be a good option for you.The few investors that I have seen be successful with these types of properties were highly involved with their investments.