We have some russets that are sprouting, if we plant them, what are the chances that we will get a crop out of them?

You will get potatoes! Been there did that, fun, do it for the heck of it!

Ok - so plant them whole? I've heard of folks cutting them up...any truth to that?

On your potatoes, there are eyes..little indentions with a little white thing in it..That is the seed. IF you have 5 or 6 of them on one potatoe, you will have 5 or 6 plants trying to compete for the food of the tater to come up and grow...Cut the eyes off, take about 1/2 inch of the potato with it..Cut it about the size of a quarter or maybe a little larger. Cut the all off and plant them about 10 to 12 inches apart....Now you will have 5 or 6 seeds quickly sprouting roots to feed the plant with plenty of room to grow...
Yes, its the truth, its how you grow them...I have bought 4, 100 lb sacks of seed potatoes, and set and cut the eyes off them to plant in the field..When I was truck farming. Those 4 sacks planted almost 2 acres of Irish potatoes.