As a non-US citizen,

Can I refuse answering ridiculous, irrelevant questions by CBP?
Can I refuse any questions by TSA?
Can TSA ask me for other things than my BP/ID (be it documents or questions) and do I have to answer/provide even though I provided BP/ID?
Does TSA have the right to inspect (as in read) documents in my hand luggage?
Can CBP force me to unlock my phone for inspection?

Basically, which rights as far as privacy/keeping silent are concerned, differ for non-US citizens vs. US citizens.
I understand CBP can deny me entry if I refuse to answer questions. But to I have to respond to EVERYTHING?

Which demands does TSA/CBP 'often' ask (to foreigners) which they aren't able to do by law?