Yes its mostly under, but I would err to caution till my money and their keys have exchanged hands :)

If I assume a 700K purchase with 590K down in a 1031 exchange and I can get $3300/mo total rents my NOI is 2.6%.

You have that process confused with a 1031 exchange, in which gains would be rolled into the new property to remain tax free, but a primary residence is excluded from 1031 treatment.

Essentially "protecting" me while riding from Exchange Place station thru the Garfield Ave station and finally to West Side Ave station where I would park.

If I choose to do the 1031 exchange, can the new identified property, a vacation rental, be in titled in both my husband and my name jointly or would it only be able to be in my name only since it was a single member LLC? 

Your best bet is to network and find other investors to exchange contracts with.  

It was relatively easy since it was a 1031 exchange and I was able to pay cash.

If you had a million in assets and 6 months of reserves they might be able to do something.If I were you I would keep buying those smaller multifamily and once you have a few more you should be able to find a bank to do portfolio lending.You can always do an exchange later on and sell those smaller properties to trade up for a bigger property.

I now own my first apartment building, a 5 unit bought for cash (1031 exchange).

Another path would be to purchase a note yourself from an exchange like FCI and document every step of the way.