Basic questions about investing in Multi-Family (5+) Apartment

[Chandra Dara]

I am thinking about investing in Multi-Family Apartment (MFA) (5+). But I have few questions:

1. Can I use a regular realtor who I worked with when I am buying my SFH?

2. I am on H1B visa status. Can a guy who is on H1B visa buy a commercial MFA?

3. If I can buy MFA, I would like to move-in into one of the apartment. Is there any advantage with this?

4. My last three homes I bought it with <10% downpayment. Can I do the same with MFA?

5. Best websites to look for MFA for sale? I used Redfin for my other homes. 

6. Best way to choose a realtor for MFA?

7. I assume I can use 75% of the rents from the existing renters in MFA towards my affordability. Is this correct?