You can buy a kickstand off a later ST2 or 4 - you have to buy it with the sidestand mounting bracket, as the '98 bracket won't work with the later sidestand. Then you don't have to deal with that crazy dogleg mousetrap of a kickstand at all - it absolutely drove me nuts when I bought my '98, especially the spring loaded retraction. I'm short legged, and the sidestand would always try to retract just as I was leaning the bike over on it <g>...
The part about the switch is harder. You can of course buy a later kickstand complete with the switch - I did. But how are you at wiring? The '98 doesn't have the wiring for that switch built into the wiring harness. So you'll have to decide what you want the switch to do and wire it yourself.
You can simply wire the switch so it kills the engine when the sidestand is down - run it into the kill switch circuit. But that means you can't start the bike with the sidestand down, and some of the members have said they don't like that - I certainly don't. A better way of wiring would be to wire so that the bike won't run if the sidestand is down and the bike is not in neutral - then you could start the bike with the sidestand down, but if you put it into gear to ride away with the sidestand still down, the bike would die. That makes a lot of sense. I started drawing up a wiring diagram some time ago for this, then never bothered to do the wiring <g>...
A very simple solution - run the switch to a dash light, so that whenever the sidestand is down a dash light comes on - make it real bright so you don't miss it. Won't keep you from riding away with the sidestand down, but it'll sure remind you...
A few more things to mention - on my bike, the later sidestand came up too high when retracted - I cut a small piece of brass and crazy glued it onto the sidestand as a spacer - figured it'd last a few days and I could see if I had gotten the thickness right - it lasted a year so I never did anything fancier.
Also - how far does your bike lean over with the '98 sidestand? It'll lean just as far with the later sidestand. This depends on how your suspension is set - esp. ride height. Mine was over so far with both sidestands that I ended up buying the Cycle Cat sidestand that's an inch longer. There were other fit issues with it, but it got rid of the lean issue, and an adjustment screw for retraction height, and takes the sidestand switch.
I guess it's worth saying that if you ride off with the stand down, the jolt the first time you turn left is mild - the side stand goes up and that's all she wrote. Not as bad as some of my other rides - I have an old Honda CB550SC, and when I hit the sidestand after leaving it down, it just about scares me enough to fall off the bike <g>... But I don't like the idea of banging the Duc sidestand much, since the side stand mount bolts into the engine casing.
Is that more than you wanted to think about? It is for me - though I've thought a lot but never gotten wound up enough about it to actually fix the problem...