OK
Answers to your questions in chrono.
•Talking about manage bookings function. Booking already made. If you have a res you can enter your booking ref & choose (& or change) seats on line.
•No not within 24 hours as we "speak". No I'm not EC (OZ). Travelling SYD-NRT-LHR. Maybe this part of the site prohibited if one is not booking within EC but a standard consumer right I can't believe it is. If that's the case I don't really believe BA can discriminate. A customer is a customer!
A customer has a right to be privy to all terms & conditions.
•Business class
•"Seating policy" within "manage my booking" must be some kind of indemnity clause I imagine.
•Once I'm in "manage my booking" (remember one must have been ticketed to get this far)I can choose or change a seat. Upon getting this far you see your seat allocation. Above the seat plan is the offer to refer to seating policy.
•I've changed seats successfully. Just can't access seating policy. Flight not oversold. Many seats still avail.