It sounds like you are planning on holding these for a while, so if the question is regarding maximizing the capital you can pull from the portfolio with a cash out refi, I think you have to look at the financial instrument you will be using to do the refinance.

Although I'm no expert in the brokerage space, I would say networking is instrumental.

That will give you a ton of information on how to structure something like this.First, I'm going to suggest getting an attorney familiar in real estate to draw up to lien instrument in PA (mortgage vs deed of trust), and also the promissory note. 

., i would use a Texas Instruments BA-35 Business Calculator which has all of these functions built in for you to amortize a loan and determine PV and FV.

The MOST important thing you should do is have a lawyer write or review your company operating agreement (if you have not already done so)I think starting out with full featured property management software has been instrumental in allowing us to scale quickly.

When signing, the big documents are the Note and the Deed of Trust/Mortgage (title of the document varies by state, but it is the security instrument that gets recorded at the county).On the Note, check that property address, loan amount, interest rate, lender, and first payment date are correct.

A HELOC is a short-term debt instrument, not one suitable for a long-term buy & hold. 

Lately theres been a new legal instrument called a series LLC.

FHA loans, Freddie Mac Loans, VA loans, jumbo loans, portfolio loans.... all of these are NOT Fannie Mae loans, so this isn't applicable to them.Section D1-4.1, Information Relating to Transfers of Ownership Applicable to All Mortgage LoansD1-4.1-01, Determining Whether a Transfer of Ownership Is Permitted (11/12/2014)[...]D1-4.1-02, Allowable Exemptions Due to the Type of TransferA transfer of the property [...] to [...] a limited liability company (LLC), provided that: the mortgage loan was purchased or scuritized by Fannie Mae on or after June 1, 2016, and the LLC is controlled by the original borrower or the original borrower owns a majority interest in the LLC, and if the transfer results in a permitted change of occupancy type to an investment property, such change does not violate the security instrument (for example, the 12 month occupancy requirement for a principal residence).Note: The servicer must notify the borrower that a property transferred to an LLC must be transferred back to a natural person prior to any subsequent refinance application in order to meet Fannie Mae’s Selling Guide underwriting requirements.Before anyone bombards me with questions, I'm not a loan servicer or a lawyer, I'm a loan originator.

Yes, transferring title from an individual borrower to an LLC controlled by original borrower is exempt from Due on Sale- D1-4.1-02 of the Fannie Mae servicing guide, allowable exemptions- a limited liability company (LLC), provided thatthe mortgage loan was purchased or securitized by Fannie Mae on or after June 1, 2016, andthe LLC is controlled by the original borrower or the original borrower owns a majority interest in the LLC, and if the transfer results in a permitted change of occupancy type to an investment property, such change does not violate the security instrument (for example, the 12 month occupancy requirement for a principal residence).