That's how it works in a CCS car, but with the adapter, the power pins are in different locations because that is the logical way to make a "dumb" adapter (without a creating a huge shock hazard with both being connected). Thus the CCS adapter can't replace the J1772 one, you still need both.
Yes. In Europe and Oceania where the Models 3 and Y, and now Models S and X, have only CCS2 ports, the top part can apparently accept an AC Type 2 (somewhat analogous to our J1772) plug for charging at home and at public AC stations. Or the entire port can of course accept a DC CCS2 plug and charge at Tesla and third-party DC fast chargers. One advantage: no adapters are required (or in the case of CHAdeMO, allowed).
I've speculated elsewhere that it seems reasonable to assume that there are external and internal pressures on Tesla to do something like that in North America--i.e., to at some point install CCS1 ports on all models and do away with the TPC (proprietary) connector system. I see that some knowledgeable TMC members think this would be a good idea; other equally experienced drivers hate that possibility.
I like the "elegant" TPC system, and have read that it wasn't Tesla's fault; the young company was forced by the big "bully boys" to develop its own innovative charging standard. But with plans to open Superchargers up to CCS1-outfitted car brands, and now with the CCS1 adapter allowing Tesla drivers to co-mingle with others at North American CCS stations, the handwriting appears to be on the wall (to me) as far as a future of DC charging standards on the NA Continent.