House Hacking - Can I do this with an FHA loan???

[Steve S.]

I found a great duplex investment I'd want to move into and purchase with an FHA loan.

Only issue is there’s a lease on both units and the earliest it frees up is in February 2019. 

1) is there an FHA rule on how soon I "have to" move in? If so, how soon? 180 days?

2) does FHA give me a lower interest rate or if I went conventional, is the only difference that I could go as low as 3.5% down with FHA where conventional requires more?

3) if #1 is a rule above, how is it enforced? I’m probably very close to whatever the days are (if such a rule exists) so is “close enough” good enough?

Thanks!