(2) Hubble is dieing. It will not last forever but still makes new discoveries, new science, regularly. A replacement is needed. And the JWST is a totally different device, not just bigger. We probably need both the JWST and a new Hubble.
The problem with colliders is that the next energy thresholds where we expect to observe unexplained phenomena are a couple orders of magnitude greater than the proposed collider. So we could really only confirm existing theories unless something major is hiding in the energy gap. This seems unlikely.
Critics want to put the money towards avenues where we're likely to observe new things instead of confirming validated theories.
And no, the higgs was a theory, now proven right (maybe you mean that by 'new physics'?)
Sorry but your view on the world is just depressing, its like we need 'new science' 'new physics' whatever that means, but building the experiment to proof a theory is right, is too expensive?
And no the JWST is a space telescope NOT something completely different from hubble, it's a telescope.