Most of the recent patches have been on days when certain Events are due to start. These Events have been announced beforehand. So, if an Event is to start on a certain date and they require certain things to be set up, then you can be certain that a patch will be done on that day.
As for your POB 'losing' things/changing prices etc, I can honestly say that I have not noticed anything missing/changing on the POBs that I look after. I have been supplying before and after a patch and everything appears as it should be.
On a patch there are no 'roll-backs'. The Files are backed up before the patch goes in and then when the Server goes live again, everything should be returned as it was beforehand, except for any System/Ship changes included in the patch.
Maybe you should plan ahead and take some screenshots, beforehand and then afterwards.
'I would like to be half as clever as some people like to believe they are' Life is full of disappointments, it is how we handle them that helps to define us, as a person