Possibly a bit tight for me, personally usually like giving the subject a bit of room to move into the frame

Seriously cool photo

Don't know but none of the big US airlines has the reg on the underside of the wing

No, 150-600mm, the aircraft was at 3000', almost had to zoom out as it passed overhead

Absolutely, delighted if you did

Yeah, guessed you were going to have to hold over here as you were so early. Any time here or quick taxi to LHR for the flight home?

Definitely not Least but could be Semipalmated, though think the bill is too long for Semi

It's a Western Sandpiper (Calidris mauri) isn't it? Least have yellowish legs