Is there a calculator for bromine like the pool calculator? Or can I use the pool calculator for bromine?

You can use the pool calculator for bromine assuming you already have a bromide bank and you are just adding chlorine (such as bleach) to regenerate more bromine. If you multiply the amount of FC that you add by 2.25, that will give you the amount of bromine you will create.

How about using MPS?

See how much Dichlor it takes from The Pool Calculator and then double that amount in volume (not weight) for MPS. This assumes 43% MPS which is pretty typical. So to raise the bromine by 10 ppm, put in an FC of 10/2.25 = 4.4 for the difference between "Now" and "Target" and set chlorine type to "dichlor" and double the volume it gives you and that's the amount of MPS to use.

Is there a calculator set up for bromine? I am using bromine powder to adjust. Or should I use chlorine?

By bromine powder I assume you mean sodium bromide which is used to set up your bromide bank after a fresh fill of water. One ounce weight of sodium bromide in 350 gallons would give you a bromide bank that could produce a little more than 16 ppm bromine. It gets recycled in that used up bromine becomes bromide again so the bromide bank does not need to be huge. There is some loss from outgassing or carry-out of bromine. I would just follow the instructions on your sodium bromide bottle for how much to add after a fresh refill and you should be good to go. Thereafter you create more bromine by adding either chlorine or MPS and by using bromine tabs in a floating feeder.