FIRST has changed significantly since it first started. I'm sure that there are a number of people who could literally talk to you for days about what FIRST was like back in the day (Andy Baker and Andy "Original Yellow Human Player" Grady immediately come to mind).
But, to hit on your specific points:
There has always been a kit of parts. The contents have changed dramatically changed over the years, and beloved parts have come and gone such as a dot-matrix printer, the seat motor and the drill motors.
For the longest time, there were no regional kickoffs. It's rather difficult to have a regional kickoff when there are so few teams in the program.
As far as material usage, that has changed several times over the years. At some points, it was less restrictive, but there were a number of years where the only place you could buy parts for your robot was from MSC and thats it (not even Home Depot).
In 1998, the control system was made by Motorola. The name of the system escapes me right now though. Starting in 1999, FIRST used the IFI control system which lasted till 2008.
Play was much rougher than it is now for sure. Check out this video for an idea of what 1999 gameplay looked like
http://www.youtube.com/watch?v=Q0CDop_IwW8 . 1997 was probably the epitome of rough play, when the current team 121 built a robot designed to gently tip over the opposing teams. This was a completely legal, and quite frankly smart strategy. Even as recently as 2004-5, gameplay was very rough (the way it should be IMHO).
Bumpers began in 2006 as an option for teams to use. Many teams decided to use bumpers to gain an extra 15 lbs., but many decided against them in order to have a smaller profile for extra maneuverability. 2008 was the first year bumpers were mandatory.
In recent years, it seems that the rules have become more and more restrictive. Before 2006, robots were allowed to expand to any size they wanted, anywhere on the field. Teams were never required to use bumpers, and could even have wedges on their robot (to limit the force a defender could put on you, and to help push people around). From my point of view, it seems that the rules are being written to force one or two very specific archetypes of robots into a game, but that's another discussion entirely.