Yes to both of these. The 'enemy' isn't the plane, it's the car, which
accounts for a much bigger share of our CO2 output. A few high-speed
long-distance routes won't attract much modal share from cars; for that,
we need more capacity and reliability on existing routes, and to restore
and build more local routes where they're currently missing.

It may go unsaid as obvious, but crucial to achieving that aim is the
development of coherent integrated public transport schemes. A good
radial dawn to late night local bus network, feeding good transport
interchanges (preferably rail, but I'll be realistic and accept
express bus routes or somesuch are more likely in this day and age).
These express routes then need to run both radially towards regional
population centres (i.e. London, Birmingham, etc.) *as well as
orbitally around them*. As a case in point, it's criminal that it's so
damn difficult to do a 11-odd mile journey near me orbitally (on the
London periphery between the WCML and the ECML), with either several
mode changes required to zig zag up and down radial rail routes
through to the central zones (which you really don't need to be in),
or you just give up on rail and stay with the expensive, infrequent,
and unreliable local buses you were using to get to the station all
the way to your destination, though you will have to endure multiple
services usually, some of which become even less frequent past 6pm.
Even with the extortionate car parking charges it can still be cheaper
to drive than use public transport, which is somewhat disappointing.
By way of comparison, it's about ~20-30 minutes by car, but well over
an hour by public transport (buses).

On a final note, ideally I'd like to catch a regular, frequent,
inexpensive bus to Watford Junction (hurrah for TfL), catch a fast,
frequent service to Hatfield from there, then continue my onward
journey from Hatfield, by train, bus or otherwise. Doesn't sound too
extravagant, but my current options for public transport between them
are either:
a) The aforementioned multi-stage local buses
b) Walking the Euston Road between Euston and KX
c) Via Birmingham and Peterborough