So my husband and his brother changed my rear breaks. New cars have this tool now that you twist the caliper instead of push it in to get the new break pad in. The caliper had more room to rotate in and the rubber cracked open while it required one more rotation or so. Is this rubber necessary? Is a new caliper needed because the rubber tore?

So it's the dust boot that tore of that helps the answer.

I've read you just wait until your next break job and relolace the caliper then. Or they have kits to replace the rubber yourself?

I have seen BRAKES operate for a long time with a torn dust boot.

My bad. I spelled BRAKES correctly in the title but didn't think twice about it in my writing. You know even though I studied English for another four years after high school into college, it happens here and there!

The caliper should not require replacement at this point. The dust boot in this case is just to keep things clean. If it's not leaking hydraulic fluid, just keep it as clean as possible and put it back in service.
An experienced mechanic should verify the brake system performance before you drive the vehicle.

How do you keep it clean? I know dirt roads should be avoided and winter weather like snow with salt as well. We don't have snow but we have property on a dirt road but we don't travel it often.