I don’t think you need to roast them first if you’re going to cook them in the microwave. If anything, it’s better to microwave first, then roast afterwards to get the crispy shell. You obviously can’t do that at work though.
The easy way to prevent them being 1,000,000 degrees is to wait till it’s cooled down before you start eating it.
I usually buy the smaller redskin potatoes, bake them at home, and then cut them up into quarters when I bring them in to work to heat up in the microwave. They don’t take very long to heat up that way, so they don’t dry out too much. The smaller potatoes are more expensive, though.
After you clean them off, poke some holes all around with a fork. then wrap in plastic wrap. That will hold the moisture in and kind of steam the potatoe. It’ll also keep them from making a mess of the micorwave if they do explode. They’re still going to be HOT, but they should be moist. I susally cook on high for about 6-8 minutes depending on size.
I used to mix tuna with some light dressing and mash it all together. Tasted pretty good.