2) If I move during the year and I want to extend or restrict the
zonal validity of my ticket, what are the costs involved?

They refund the difference between what you paid for the annual and what it
would have cost had you bought monthlies and weeklies, less an admin fee.

The annual is the same as 10.4 monthlies so at 10 months no refund is due
and from about month 8 on the refund might not amount to enough to buy much
at all.

I got caught by that this year having gone into hospital with a month off
work. I expected they would just extend by a month but by the time they'd
worked it out and taken the admin fee off, there wasn't enough left from
the 4 month refund to buy two monthlies to take me up to the end of the
year! Just had to take the hit of 36 days travel paid for which I couldn't
use. Take off the leave and courses where I didn't use it, monthlies would
have been cheaper.

Cheers,
Dave