Also, your credit score may be higher than @Richard Moreno's. 

My wife got into the military and has now graduated Basic Training and is now doing AIT school training she is receiving a bonus of $25,000 $10,000 in cash when she finish AIT school in May and we both have good credit scores mine is about to go up over 700 hers is in the Mid 600 range.

Doesn't it negatively impact my credit score every time I ask a different bank if they can prequalify me?

All of the aforementioned are consummate professionals and incredibly experienced.

My question is does anyone know if accepting the HELOC, but not accessing it yet, will affect our credit scores and make it more challenging to qualify for traditional mortgages.

We have several properties we have analyzed and the numbers are incredible!  

They will look at you for credit score and criminal background but for the most part it's based upon the properties ability to generate enough profit (NOI) to service the debt (principal and interest).  

BP is also a truly incredible place to network and link up with those people that can get you involved with some hands on first person experience.

@Isiah Ferguson If anything, it's the credit score that is inflating the interest rate.

@Charles Bright  Rates are based on the type of transaction (purchase / refinance / cash out refi), occupancy (owner occupied or investment), credit score, loan amount and percentage down payment, property value or purchase price, and property type (SFR / 2 unit / 3 unit / 4 unit).