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?

It seems a lot more intuitive and user friendly than the other one. 

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.

I use quickbooks for my rental company and they have an online payment system called IPN ( Intuit Payment Network).

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?

It was ok but I have actually found QB more intuitive for me and switched to QB online.

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

So see how they’ve done with their own stuff up to this point and choose wisely based on intuition, gut-feeling and physical evidence.So the car inspection is over now.