I purchased for $420k and the house needed quite a bit of updating/fixing and furniture, so I spent another $64,000 in repairs using my savings along with credit cards...yeah...ouch...I know...  

run out and get a pre-paid credit card and/or a "normal" check card ASAP.  

I just stopped in, spoke with a manager and told them I was wanting to put a card on file to be used up to $200 on a Friday morning.

Would you use a credit card to furnish your rental? 

I paid by credit card. 

Should we open a zero line of credit (through home depot, credit cards, loan?)

Then when you don't have the money for them they coerce you into getting credit cards to fund the program they promote at the seminat ,promising you you're going to make a ton of money so don't worry about the amount of money your putting on credit.

Prospective residents could be required to answer customized landlord questions while also needing to provide a valid credit card prior to entry.

@Kelly O'Keefe For more context, we have a business checking account which we have made capital contributions into, and we have put the business expenses on the business credit card and have paid that card off from the business checking account. 

Then when you don't have the money for them they coerce you into getting credit cards to fund the program they promote at the seminat ,promising you you're going to make a ton of money so don't worry about the amount of money your putting on credit.