I have always used 15-30 year fixed rates, but I have been reading about ARM's as a possibly better option depending on how long you intend to have the financing or the property.

A little more complicated than I have dealt with, but if the asset qualifies as a capital asset it would depend on length of time held as to Short term or Long term rates.

If you want your contract to be enforceable then provide equitable consideration, not this $100 junk.0 interest will really tic off a seller when they have an imputed tax on interest and depending on how you led them to accept such a deal can take you to court.

Finally, the state of incorporation shouldn't matter, it just depends on which state laws you want to have the LLC follow.  

My understanding is that the cost of the insurance will depend on the flood zone rating.

The costs run 3-4 points + 8-12% interest only payments depending on your experience/credit/property.    

Don't pay too much/any up front, depending.

You might look into form some type of corporation or a LLC depending on your financial wealth.  

Most places have an average fo $600-$700. depending on area.

If they paid 1st and last months and a security deposit then you possibly could keep that but it would really still depend on what's in your lease.