I can answer, sort of, one of your questions. At least, I know one interpreation of the word jazz fushion.
In the case of the Welsh guitarist Shaun Baxter (first album Jazz Metal) it was very much the case of taking the typical jazz lines, eg. using melodic minor (aka Jazz Minor) scales, complex chord structures, progression and changes, but playing it in a non-standard jazz form. A little...crunchy I guess.
Really, as I'm sure you already know, fushion is just a merging of two different styles. Often jazz fushion is more geared towards rock ideal...
I know that's very badly explained - and I don't claim to be any sort of expert on the matter. Non-the-less, hope I helped some. Anyone any takes on it?...