Hey folks, firstly like to say hello to all!

Ive just bought my first astra, its a Y reg, 1.6 club and so far shes been great, but i have noticed one thing thats got me puzzled, Ive quickly searched the site but cant find the answer, when i remove the keys from the ignition the stereo goes off, but stays lit up (Its a standard vauxhall job) I dont think the electrics have ever been tampered with, im a little worried that this will drain the battery if left for too long, anyone got any ideas?
oh and another quick thing, its due a service (INSP showed a couple of times) but now the engine light has come on, (in the manual it shows the icon with a little spark in it) is this to tell me the service is due or is it something else like emissions/exhaust?

any help would be greatly apprieciated, thanks