- or automatically from the Oyster readers if you have auto top-up
enabled, of course.

Either the rules have changed since I've last looked at them (not being a
regular user of PAYG) or they were badly worded at the time - I was always
under the impression that one had to nominate a station for collection
which wasn't much help if you lived by a non-PAYG station and couldn't be
sure where you would hit your first Oyster reader. (Does one actually have
to travel from the station nominated for activation or could one just
touch in with a season ticket at a standalone reader and then go and use a
bus or season?)

You have to nominate a station to load fixed amounts of 'top-up' ordered
online onto an Oyster card and you will also end up being touched-in at the
same time and so have an amount taken off your card. However it was 'auto
top-up' that was being talked about and that is a different animal. Auto
top-up is triggered by any touch-in on buses, trams, tubes and presumably
trains.