I don't really know the answers to your questions Steve, but I'll tell you what I do know.
The obvious difference between 95 and 96 was that the 95 retained the Tange Ultimate seat tube, enforcing the fitting of a conventional-swing fm. And as you say, they changed the dropouts from 97, possibly because of the breakages suffered with the previous design (fingers crossed all round!) I personally haven't seen any detailed technical specifications earlier than the 97 ones, but if anyone has an owner's handbook from those earlier times they were no doubt in there. [there must be thousands of them out there, and I'm a buyer!] The 97 frame was described as follows:
"Constructed entirely of Columbus Nivacrom Max OR tubing. Tubing wall thickness: Top - .7/.4/.7, Down - .8/.5/.8. The seat tube is custom drawn for Kona by Columbus with a wall thickness of 1.3/.6/.9 Columbus-drawn, oversized seat stays dramatically improve braking performance."
That's fairly explicit - the entire Max tubeset was used (contrast with the later 'True Temper OX' Explosif, on which only two tubes were True Temper, and the rest were generic 4130) Clearly the seat tube shows that wasn't true of the 95 frame, but whether Columbus stays were used in 1995 I couldn't say. The 1996 frame looks just like the 97 aside from the dropouts, but again I have no idea what stays were used.
I can tell you though that the 96 Explosif weighs 40 grammes less than the 1997 (Columbus Cyber) Kilauea on the same scale and on a size-for-size basis. Nothing extraordinary about that, I hear you say - but the Kilauea had lighter top and down tubes than the Explosif, and the same seat tube, so the Explosif must have been a lot lighter elsewhere - essentially the stays. i.e., Cyber is also heat-treated, so the top and down tubes on the Kilauea could also be 7-4-7 and 8-5-8 in gauge, but the Kilauea has 28.6 and 31.8 tubes, whereas the Max tubes were 31.8 and 34.9 (both bi-ovalised obviously). I estimate that this would add c50 grammes, giving a stiffer front triangle on the Explosif. And if this means that the Explosif was c90 grammes lighter elsewhere, it implies more compliance elsewhere. My assumption is that the Explosif was seen as the ultimate steel xc racer, the Kilauea less so. Your weight for the 95 Explosif frame, albeit on a different scale is closely in line with mine for the 96, so my assumption is that while there were changes in spec, they didn't make a lot of difference.
As you say, the bi-ovalising made Max expensive. I understand it first came on the market in 1988, but I don't know anything about its subsequent development during its production run. i take it that OR was the mtb version of it. As things go, I imagine it was fearfully expensive to begin with (as 953 is now). Things need to be cheap to catch Kona's interest, so maybe Max was nearing the end of its shelf life by the mid 90s and they were able to cut a deal. Cynicism aside, Kona were clearly more willing to spend money on the frame in those days, given the contrast I touch on above. I guess in the mid 90s, the frame was everything, whereas by 2002 both the fork and the brakes cost more than the frame, so why spend money on fancy stays?
Here are three pictures of the Max frames in chronological order