Mega jolt just controls spark, where as mega squirt controls spark and fuel injection. If you were to use the Devils trumpets then you would only require mega jolt
dont be put off by how complex it seems, it is deceptively simple. I had no experience with auto electrics before I fitted mine and found it relatively straight forward.
if I were doing it again I would get the later 4.0 to do away with the need for a dumpy dizzy as you say. The megasquirt/jolt does not need it, it is there to drive the oil pump on the v-belt engines and to just plug a hole on the serp engines