The mortgages on  these are at 8% with 25% down.

If you do the LLC, you will need a commercial mortgage which has higher interest and a bigger than 25% down.

Junior lenders redeem last minute.. 

If I got a Heloc, once the property is built, could I get a traditional mortgage and pay off the heloc and then tap into the new equity as well?

Looking for a Texas lender that can answer some questions or give opinions on doing a cash out refi on a rental property to help pay off personal debts. 

I'd also start talking to lenders and agents who have experience with investors and experience with the strategy you're looking to pursue.Best of luck! 

In such a case, you need to close on your A-B transaction with your own capital or that of a lender, then have a second escrow and closing with your B- C transaction.

Most banks and traditional mortgages "Do not" allow foe the property to be vested or quit claimed into an LLC unless it specifically states it on the closing disclosures.In most cases even on DSCR loans the Bank/Lender still requires you to sing a personal guarantee even if they allow the loan to be vested into the LLC.  

I'd Airbnb the 1st home & would do new construction on the 2nd lot.Am I able to bundle the purchase of both the house purchase and 2nd undeveloped parcel into one mortgage?

Taking over his already paid down loan at 3.5% for 28 years saves a ton of money and no bank qualifying or lender costs.