The most commonly accepted rules are the Larry Harris Tournament Rules, and they clarify many of the ambiguities (and outright msitakes) of the rules manual provided with A&A (revised, aka Avalon Hill version).
There are previous discussions on this board about the screwed up printed manual rules that SPECIFY goofy things like SBR damage being the roll of the dice, or the IPC vale of the territory WHICHEVER IS GREATER.
On an amphib, unless, you are using a house rule for aerial retreat, then ALL attacking units, regardless of type, remain until combat is completed in the case of an amphib attack.