[Strider]

Base Raids : One light cruiser can 'destroy' a minor base that isn't built up very far. The more firepower you put on a base in a raid the more damage you will do to it. As for air on bases, yes they can do a lot of damage to a couple of CLs, but the more ships you put into a Raid, the more the aircraft will be divided up into attacking, and the better odds that most or all your ships will survive.
As far as night raids, they do occur. John can explain them better, but it has some to do with how far the attacking ships are traveling, and maybe some randomness.

Withdraw : Withdraw is not always guaranteed. If the attackers have chosen Surface battle, than they can 'chase down' slower ships that are attempting to withdraw. I've noticed that usually, if I have a light cruiser patrolling a base and it is attacked, it can't get away, tho sometimes it does. So yes, you can suffer 'pursuit'.

Don't know about shipping dates, that's a Shrapnel question.