The property is worth about $210k.Title will transfer to his SDIRA.

My question is am I able to transfer this property that I own into my holding company and still be able to use my heloc without any issues.

I was toying with the idea of taking the transfer, buying a house (or multi?)

Auto transfer gas&electric into the owner name might have really big bills, besides you don't have to turn gas on in summer.Same with water: if you don't bill tenants for using water - make sure that the owner agrees.

At this time I would pressure them to replace the unit (warranty should be transferable) and they will fix the noise prroblem.

How easy would be to transfer my 4 rental properties to the LLC? 

I would rather consult my owner financier and ask if they would accept a transfer of the loan to another person but that probably means you will not be able to profit as you imagine for such a transaction.

Are most new investors getting a mortgage under their own name and transferring it to the LLC?

Your selling closing costs are too low, philly has a 3% transfer tax.

As long as the purchase price is enough to not leave a lien on the property you can transfer clean title.