A few quick data points for you:1) In order to do a VA IRRRL (which is still a VA loan), you must have a minimum of 210 days from the date of the first payment on the first VA loan to the new note date (i.e. closing date of the IRRRL).2) A minimum of 6 months consecutive payments must be made on the original VA loan.I'd first look to see if you have any VA entitlement left following the 4-plex purchase... if not, perhaps consider a refinance to an FHA loan while it's still your primary residence (loan amount can be up to 97.75% of the value of the property if it's a rate/term refinance) in order to reuse your VA entitlement for another purchase down the road.

However, on your primary home it will be more strict as there are a lot more federal compliance rules involved. 

Something part time when you are not at your primary job.

HELOCS on your primary tend to go up to 95%, but the higher the LTV, the higher the rate.  

I am getting HELOCs on my primary residence and a rental property, that my husband and I own under our names.

If you're worried about your primary lender knowing, and she's okay with it, you could do a unrecorded second (more risk for her).  

My wife and I are moving into one of our apartments (4 plex) and I'm wondering if, because we will be living there as a primary residence, are we exempt from any of the renting laws?

Keep in mind in my case I have an 800 credit score, two rentals, and a primary home if that changes anything from the banks point of view.

Yes you're supposed to live at the property for at least one year as your primary residence which means at least 51% of the time. 

I don’t think this would get the tax breaks you get for a primary residence