I was thinking of taking one of the properties and refinancing so I could do an additional purchase and possibly flip to generate cash. 

@James Miller Yes, I know you have to use the available section for additions or add an addendum to the base form to make a series LLC from the standard form to file with the state.

This RE company says that they provide additional training and they want me to sign a contract to be an agent with them.  

If the LLC is involved in the management of the property it may be able to be listed as an additional insured. 

Yes, this can be a huge time saver especially if your jurisdiction considers this an "addition" instead of a "new construction" which generally makes it easier and faster to get a permit.

I would try to get an optional 15 day extension with additional EMD, if possible. 

These are professionals with additional training and a stricter code of ethics.

I’m just getting things started and want to get into ‘buy and hold’ properties to bring in some additional cash flow.My wife and I have a decent amount of funds set aside, but I was wondering if it makes sense to open a HELOC on our primary residence and utilize some of those funds as well for a down payment.

You can list your unit on there, as well as do background and credit checks and collect rent.In addition to asking a local realtor for the rental rates, you can look at the rents of similar properties in the area, which you can find on places like Zillow and Apartments.com

Additionally I invest purely for cashflow.