a. You can run local and express trains if you have station sidings. Standard practice all over the world. Local train waits for the express to speed through.
As I said - stations yes, sidings no. However, I think the kind of passing loop you are talking about may exist on HS1 to allow limited freight services through. HS1 has 30 Eurostars daily + 4 SE HS trains each hour - a little room for manoevre. They want 24-30 tph on Crossrail, 18tph on HS2 - remember it isn't just about getting out the way, when one train runs slower or is decelerating, the other catch up very quickly.
Also, tunnels are bored using TMBs - I imagine more tricky to keep boring out parallel tunnels. It really isn't a runner, forget it.
b. They have not explicity published the two routes (HS2 and Crossrail) combined and anotated, so one can see the grand plan (if such a thing exists). Does Crossrail appear on that map-link you gave? If it does, it is not obvious.
That is because they are two separate projects - Crossrail is already being built, HS2 needs to go through the Commons, then the Lords to become a hybrid bill / act.
Yes - at this stage, Crossrail is out of the tunnel (that is just west of Paddington), so the 8 platforms to the south are for Crossrail, heathrow Connect and FGW (or their successor) services. Big if - will they roll Heathrow Express in for T5 access - they certainly should!
c. Not necessarily. When ever I travel on TGV, the main northern hub in France appears to be CDG - I have not been linked through Gard du Nord once. If you want to go to Paris you take a Paris train, while everything else goes via CDG.
When I have looked at timings, trains from the south usually stop at CDG and then continue on to Lille etc, so they are not just serving the airport. A through station is much more flexible than a stub - and that is why I think the rail link that runs through LHR needs to continue to Reading and onwards. AMS, FRA, CDG are all through stations.
I would imagine a 17-car train splitting at Silver-Boris, with 5 going to London and the remaining 12 carriages carring on to the North of England.
But a train needs a nose at each end - so that would be completely un-even, and also, demand would be the other way round. Also, calling at this island would add - I guess a good 25 minutes to the time of any train using the HS1 line. Totally different to skirting round Lyon and Paris, where the mileage might be a bit more, but you are cutting out a very slow trundle through the city.
e. Ever been to Lyon station - the dinosaur carcass??
As it happens yes, and it was the inspiration for a major decision I made a few years ago. It is a wonderful piece of sculpture. However, LYS is a REGIONAL airport, which has only just build a rail link to the city.
La gare est un éléphant blanc
f. St Pancras and King's Cross are one and the same (300m between them), and I call it Kings Cross as that is the name of the tube stop.
Well done, we've gone down from 2km to 300m now
No, the tube is King's Cross - St Pancras.
If there was a 767 next to an A380 on the stand, would you call the Boeing an Airbus? In aviation terms, EWR is right next to JFK, but would you try and check in at one for the other?