Investing in multi-family

[Anand Acharya]

Hi all, 

I am a complete newbie to real estate investing. I have a condo rental but that is something I rented out after I moved out of it and did not want to sell. So it was not bought with investment in mind. Although I am not losing money on it, I want to expand my investing portfolio.

I have a few questions about buying multi-family properties:

1. What papers should I be inspecting before I go into inspecting the units?

2. What are possible red flags or concerns while inspecting the units?

3.  If the tenants are currently under lease, do I have to wait for the lease to end before I increase the rent or make any rehab? what about the ones who are on the month-to-month leases?

4. Can I use rental condo equity with HELOC to pay the 25% down?

5. Is it wise to use interest-only loans or better to go with traditional lending?

TIA.