So has this “eclipsed” Hubbell...or replaced it?
Eclipsed is probably the right word. Hubble will be around a while and can be serviced. No such luck with the Webb.
Neither. It is a separate instrument placed at L2 which gives it a great dark field to look at
It was designed and built to capture first light
Once fully operational it replaces it as our best telescope. It can see further back into history than hubble can.
Hubble will be a spotter scope looking at areas of interest, then JW will look at those areas in detail.