Last Dec was no different, i send in the money for the license, fill out info and expect a reply shortly thereafter.

There is a world of difference between $50k cash flow unleveraged and $50k cash flow from a highly leverage property.  

To me I never notice a difference and pick light scents just to keep my home smelling nice because its an older wood home in the country and sometimes gets a different smell to it that can be a turn off.The guest lost it on me after arriving and said she had asthma and couldn't stand being in the house and wanted a full refund.

To answer this I would look for similar rental listings with the only difference being what you mentioned above.

This was great for me because I knew the US property market was a totally different beast to our Aussie market, and although I was getting myself educated in the differences, having a fellow Aussie on the ground would be very helpful.

Different agencies or? 

It is no different than any other business relationship. 

LLC or not won’t make a tax difference. 

When filling out the IRS SChedule E for a multi unit property, do i list each apartment separately or do i have to list it as a "property". 1 "property" has 4 units or apartments with different rental days and expenses, etc.

I'm not sure if you've retaken photos of the same room from multiple angles or they are different rooms.