No reason to do that. Car now has 400 or so miles less on the clock.
That wasn't my experience. The National rail website allows you to get prices depending on which train you take. In our case we could travel off-peak and I have a DOF [1] railcard too.
In this case *lower* costs. We were staying city-centre for a few days and it would have *cost* to park the car during that time. So we walked from the station, not far although I wouldn't have wanted to do it in heavy rain. Nor would I want to do it frequently, but then that's also why I've always avoided any job that involves commuting.
I agree that's a bit unusual, but if the situation arises then do it.
Depends where you're going.
See above. Certainly if we're doing a day trip to London, we'll take the train.
In general, I'd say that we shouldn't be looking to build more high-speed trains. Instead use the money to upgrade what we already have, f'rinstance.
Or possibly scrap the trains and pave over the right-of-way, to be used by lorries and buses *only*.
[1] Doddering Old Fossil