I'm not so sure about low demand for BA. As mentioned above, the move from a once a day 787 to a double daily (mostly) 321neo, is a doubling of both flights and seats. But I'm sure you're right that the reduced costs of the short haul operation will better support lower priced tickets during periods of low demand.

As others mention above, getting an online visa helps with the arrival process, allowing you to head straight to the immigration desk. You still need a landing card. These are normally handed out on the plane, but if not, available at desks just before the immigration desks.