Hi

Take a look here - you'll find some answers for your questions:
[uboatarchive.net]
Chapter IX Damage Control, 4) Escape from a sunken boat.

There is no sense to flood only the conning tower - to keep the control room secure from flooding,
the hatch leading from the control room to the conning tower had to be closed - if so - how you will get out?

The ways of flooding (and the time of flooding) is given few pages further
(Flooding control room and conning tower)

If you have questions - go ahead, I'll try to clarify.

--
Regards
Maciek


[www.tvre.org]