The Shimano Di2 SW-R610 Remote Sprinter Shifter Set is designed to be mounted in the drop section underneath the handlebar tape. Just cut a hole in the bar tape so the shift button is accessible. Each Sprint shifter plugs into a dedicated port on the 11-speed Di2 STI levers.
All Di2 components on the bicycle require the same firmware version. Using Di2 components with different firmware versions may cause malfunctions. Use Di2 system checker to update component firmware from http://e-tubeproject.shimano.com/