Agora will work installed over the basic elemental theme install. The caveat being that not all of the blocks from the core install are styled for Agora.
There are currently 3 presets available. Unique looks can be achieved with 5 page colors choosers as well as body and header font pickers. If you need a stylization not available please drop me a note and I'll see about getting it included.
The autonav block uses a custom template called "Slicknav" to activate the mobile menu. Please choose this when setting up this theme.
The "Main" area is indented from the center line on non mobile screens. Above that is a "Gallery" area that will stick to the center line as well as the line dividing the header.
While in edit mode you will notice that the main area will snuggle up to the divider line. This is due to the core css using a name this framework uses. It will disappear once you are out of edit mode.
Problems? Issues? Praise? Contact me thru the concrete5 messaging system and I'll get you sorted out.