When you say window not working as it should...do you mean not raising or lowering after a few second depress of the button? If so, with the window fully up depress the up for a few seconds and that should re-set it. This will hapen after disconnecting the battery.
The stereo code - mine was on a credit card size card in my cars manual pack-up ....... was also written in pen on the wiring diagram on the stereo itself by the previous owner lol.
As for the petrol left, the ECU will have probably been reset depending on how long you left the battery disconnected for, this will settle as the computer gets used to your driving style again.
............hope some of this helps, others will add should I have waffled rubbish.