Grilling / broiling the potato after it comes out of the microwave is quicker than baking it and achieves the same crispy outside.
If you really prefer them baked though, you can speed this up by inserting a large metal skewer into the potato while it's in the oven
First, potato is not the same as potato. Conventionally, potato salad is always made with waxy potatoes, because mealy potatoes' outer layers disintegrate when tossed with the sauce, much like making risotto. They are also less creamy in texture. But there is also the school of using mealy potatoes, because they absorb more seasoning, and also because some people like the soft texture. If you decide to go with mealy, use an acid in the cooking water (depending on your seasoning, choose vinegar, citric acid, or the neutral tasting cream of tartar). This will firm the potatoes. It isn't necessary for waxy potatoes.
Second, the cooking time depends strongly on size. You must cut them very evenly. Else you will have both undercooked and overcooked potatoes in the pot at any given moment (up to the time when you only have overcooked ones). Smaller pieces are easier to work with.
Third, you want to heat them as gently as possible. Start them in cold water, and cook them at a simmer, not at a boil.
There is no way to predict when the potatoes will be ready. Even if you cut them to the same size every time, the sort and the age of the potatoes will result in varying cooking times. When the time is near, you must look after them and try them constantly. Take out a piece, cut it in half, cool it in cold water, and chomp on the exact center. If it isn't crunchy, stop the cooking immediately and remove the water. The time window in which they are just right is quite short. Season them while they are hot, they will then absorb the sauce instead of just swimming in it the way cold potatoes do.
Best Answer
Since I cannot speak to the benefits of the convection or grill modes of your microwave, I would use the main setting.
In the context of a salad setting, although you want moist meat, sausage would produce a bit much grease. If the grill setting can actually cauterize the meat without creating too much grease, or if you can capture the runoff (i.e. with a bacon microwaving plate), it would be more beneficial. In many cases, though, the microwave will soften the sausage, then cause it to dry out (again, you will want to capture the grease for the sake of the salad). Nonetheless, it seems like the microwave is a poor alternative, and (if it is smoked/pre-cooked sausage) you might better to just eat it cold.
That said, if the problem is that you are just looking for an alternative to steaming and then frying, have you consider braising, searing, grilling (if possible)? You could also do a marinade to moisten the meat and then do a quick, very high-temp fry (in a skillet) to just crust the marinade and heat the meat. These all seem faster or simpler than steaming and frying.