In addition, we can lock a rate while they are still low for a very long time.My question: HELOC or mortgage?

Inventory is still at an all-time low, and we've basically accepted that as the new normal for the past few years - especially due to the fact that there is practically no development in the SFH arena - only for new apartments/condos - and those can barely keep up with the demand. 

On a different topic, I was sad this AM when at Lowe's, they didn't have seed one for winter gardens. 

Keep in mind I am looking for a low cost broker (no desk fee, monthly fee) given that this will not be my full time job.

My wife and I are 60 mechanics at Lowe Field.

If experience level is low.

This would be my first effort, as a non-accredited investor, dipping my toes into real estate in a low risk way. 

As far as your actual question goes, it is hard to say with absolute certainty what a flip will do to a neighborhood.

We want to go for another real-estate investment (we are doing buy and hold..buy low, renovate and make them short term rentals on airbnb in Ocean City, Maryland).

Used all the money plus brought in 20 k to make the rent low enough to make sense and be safe.