This is mentioned over and over but could someone lay out a clear explanation of said expenses?

Zillow I don't believe provides you ability to transfer their code/ layout into another website.

To me, it seems like it would make more sense to get a fourplex (higher cash flow potential and spreads the risk in case of vacancy), but so far, the Duplexes seem to be a lot nicer, a bit better fixed up, and have better layouts {ie. dual garages}.

What should I expect to pay for 10x10 layout?

But I recommend you clearly lay out everything you need for potential agents, get their commitment on it, then bring it up if they are not meeting your expectations.

NOT a great layout idea!

I know that it isn't that hard to create a 3/2 out of a 4/2; is this worth the time and effort along with the money to change the layout of a rental for a better marketing strategy?

The cantilever seems to add just enough extra space to make the layout work.

I also look at opportunities to create legal second units in places closer to downtown where the layout may lend itself to this, and where it is allowed.   

Rather than requiring the potential tenant give me an email address, I offer them something best suited for email e.g. photographs, floor plan layout, copy of the utility bills, full copy of the lease....It is a play on the classic "Take my hand" versus "Give me your hand".