Singleton creation and usage

How do you go about creating a singleton to join a pool? Is it possible to have 2 or more singletons so that you can farm to multiple pools at the same time (obviously with different plots)?

AFAIK there is one singleton per public key. If you want more than one pool participation, you need multiple keys. Each plot is dedicated to a key.

Is that the same as multiple wallets?
Under the “Keys” tab it shows “Select Keys”, and you can have multiple keys/wallets?
So, if I create multiple keys/wallets then I can have multiple singletons, with each plot belonging to one set of keys?