If you pay into Social security for yourself, you also pay into the Unemployment tax system for yourself.

Where do I deduct the mortgage interest, on the original property used to secure the loan? 

Background/credit check, income verification, talk to their last two landlords, talk to their boss, move-in inspection, security deposit, etc!

Maintenance fees are usually really high in HI and this one was reasonable at $650/mo with a pool, prime location, and 24hr security.

We are securing with loan at end... 

Because you likely won't be able to secure another FHA loan after your first purchase, starting with a bigger, more expensive property might be smarter, assuming that you don't have unlimited cash reserves.

Similarly, it's difficult to quantify how much a secure bike rack is worth, or the proximity to a bus stop.

What security system can be used so I can monitor activity there?  

Remember conventional all go through the same underwriting and end up on the same balance sheet (one of the governments secured entities) no mat who the originator is.

I would recommend talking to a securities attorney who specializes in real estate like Jillian Sidoti over at Crowd Funding Lawyers.