I'm struggling to understand the proof of stake concept. As I understand it, in order to participate in validation and its rewards, you must ante up some ether (I was told a minimum of 32). You are then punished if you act badly. I'm told this would include being offline for periods of time. Does that mean that if you decide you no longer want to participate in validation, you lose whatever your initial ante was? I guess I'm asking if there's a scenario where you can get your initial deposit back.
Yes, as a validator you will have the ability to log out from the validation group. This will be done calling the log out function of the dedicated PoS smart contract. Then after a delay during which you still have to validate, you will be able to withdraw your initial deposit. See Casper validator guide for more details.