The Federal Tort Claims Act would provide an avenue for suit against the US even if it's no longer possible to hold individual officers liable under Bivens.

2/ If you notify foreign students can either leave of their own accord or at least in theory challenge the revocations. Non-notification allows plain clothes arrests on the streets. Clearly the only rationale for the non-notification is to spread the penumbra of terror far and wide.

it’s deportation in the same sense that Jews put on trains by Nazis to be “resettled” in camps in Poland were called deportees