This is a great BP blog post about analyzing for STR:https://www.biggerpockets.com/...It even includes an excel calculator that is pretty good.

This was a primary residence for 8 years, a rental for only one or less.The good news is that it does qualify for the Section 121 Exemption, which is a better plan if you qualify. 1031 essentially passes the buck on the tax bill, Section 121 ELIMINATES the tax bill.It sounds like you qualify - you lived in it as your primary residence for 2 of the last 5 years (actually 4 of the last 5).

Well I think the good news is the refi from the deal itself is going to take its rental income into account for the DTI calculation, while DTI from the initial HELOC will not. 

Looking for a General construction contractor in the area with excellent track records with similar projects. 

So I can’t find a simple answer as it’s only one piece of puzzle- as supply and demand have huge impacts.Anyway, the good news is if you are really holding for 10-30 yrs, you don’t have to worry about this (too much). 

When I first applied I estimated my home value at 390k which would give me a line of credit of 62k at an 80% loan to value ratio. (390k x 0.8 - mortgage balance)The appraisal came back at 420k which great news however when I requested that the limit be moved up to 80% LTV of the appraisal amount (86k) I was told that the loan commitment had already expired so in order to get up to 86k it would need to be a new application and also I would not get the promotional interest rate of 1.99% for the first year.

Good news is that you're receiving around $350 a month in principal reduction.

While qualifying for a HELOC is dependent on your home equity and your credit score, good or excellent credit makes it easier to qualify.

I am compensated unbelievably well for my work, and what's even better, I'm compensated in both increased rent and equity, not a one-time paycheck.The bad news is, you can look forward to at least a five-year apprenticeship, you have to have reasonably good hand-eye coordination, the job is more dangerous than most, you get no respect, and you'll spend too much time alone trying to motivate yourself.

Good news.