1. Yes, that's OK at the moment, just fill in the PLF. You could stay overnight if you wish, but you need to self isolate at the hotel.
2. Nope. On past performance, things will be very different from today.
3. It's a largely point to point route, and where BA has an effective monopoly. If they had to move something over to LGW, presumably to retain slot presence, then this is was an easier choice than the other options.