Switching to snow tires- Iowa winter?

Yeah, don't do that. If you can, switch them all. If you can't do that, then don't switch any of them. If you switch only the front ones, then when you brake, all the tires stop turning, and the front of the car (with the snow tires) stops moving forward, but the back of the car (with the regular tires) moves sideways, spinning the entire car around. At best, you wind up facing the wrong way. At worst, you slide into the car next to you or you go off the road.

If you like spinning out on ice then by all means just put the only tires with traction on the front. Just remember that a loss of traction at the rear of the car WILL result in a loss of control of the vehicle and most likely an accident.

No wonder then no reputable tire shop will install only 2 winter tires.

Switch all 4. If you are finding a lot of ice, and studded tires are legal where you live, get some. However, they limit your top speed and damage bridge decks. If you buy rims too, you can swap them yourself, or a tire store may offer free storage and swaps with a purchase.

Switch all 4 to prevent the back coming round.

As with all tires get a quality tire. It is your only connection to the toad.

Unless they are studded, snow tires will still slip on ice. Buy some steel rims for your car at a junk yard and have the studded tires mounted on them.

As mentioned, you should change all 4. Otherwise the rear of your car will have less traction than the front and will try to pass the front of your car when braking or turning on a slippery surface (a spin).

Yes you can, your front tires are your main concern.

Switch all of the