In our 3 properties, we typically run a less than 5% vacancy, actually its less than 2%, but I always take 5% of the monthly rent for that emergency fund in case I run an eviction that lasts several months. 

Alternatively, you can try to get a private money loan or ask the seller to finance a portion to reduce the down payment, but typically equity is the preferred method when you need funds for a down payment.

Finding residents is a completely different process as compared to a typical rental property (assuming you are operating legally).

Best way is to get a payoff on the account which i typically do during the research and consultation stage with the client. 

Typically on short sales the IRS will issue a partial lien release.

The rental typically wont add much or any to your debt ratio, because its offset by the rents.

When you get into larger stuff clients expect you to have vast experience, a large network, and systems set up.In commercial as an agent starting out or whatever they label it in your specific state you typically join a firm that specializes in commercial sector like only multifamily, only retail,etc.

Other than your typical roommate complaints that you would have in any house, I didn't have any issues.

Typically, though its highly variable, for a rental you could do cosmetic work (e.g., paint) but nothing that requires a permit. 

@Abena Cannady Yes, an inspection contingency is normal, typically 5-10 days so 3 days should not cause objections.