IDI sells the parts to connect the RQ to a hose bib and we even sell hose bib timers, so no, you do not need a sprinkler system.

Yes you can, ideally to a ½ drip line directly into the valve on the RQ. Be careful to balance volume between the RQ and the rest of the system

The RWS has several different sizes available and you have to know the soil conditions and tree needs before buying. Also there is no way to increase or decrease water volume in the RWS and no practical way to fertilize in their device. With the Root Quencher you can adjust the flow, the depth of the device and mix fertilizer in the chamber. One size fits all needs

Yes it is, and when setting the RQ valve, be conservative on water and set it to fill once during the cycle (1 gallon).

The Tree Gator is a bag that is placed around the tree trunk filled with water that seeps into the ground to water. The RQ waters in the ground at the roots.