Its tough to give a spot on answer as I don't know your credit profile, terms of the loan etc, but a 6% interest rate for a non owner occupied property may not be too expensive.

My credit union has offered me a great interest rate for a secondary home.However, they stated that the bank will not allow me to put the property in an LLC, after the purchase.If I can purchase this property with a great interest rate, can I refinance, after a year, with a major bank, and place that property under a LLC?

Do you have credit cards?

I'm looking to work with an experienced real estate agent who is familiar with the Cincinnati area and has a proven track record working with investors. 

I’ve found a commercial lender that will give me a line of credit on 80% of the combined equity of the properties. 

You're on the right track!

They had bad credit and couldn’t just get a loan to pay off their taxes.

I have talked to a couple of local credit unions and either I got connected with the wrong person or they are not very generous on what they are willing to provide as each of them were not quoting very favorable terms.

I think most lines of credit won't have an amortization schedule, because they are meant for frequent smaller purchases, I have no clue about the rate though.

. - Self managing a couple units is a great way to learn the business.Property Management Software - check out something like Cozy.co - it helps you list/market your units for rent, lets prospective tenants apply online and does background & credit checks, then once you place a tenant they can pay online along with submit maintenance requests.