I usually use two different brushes - soften skin and exposure increase brush. Can I create two brushes and switch between them with hot key instead of changing brush options all the time?
Use the "/" key to switch between the brushes.
For your info, here are all kind of Lightoom shortcuts from the always helpful and gracious Lightroom Queen. Victoria Bampton. You might want to check the rest of her site as there is a lot of info there.