General questions on how services are provided

I was wondering if anyone on this forum might be able to answer a few general mobile phone queries:

• 1a) How do operators identify an individual phone?
• 1b) Is there a MAC address like on computing equipment?
• 2) If there is why aren't stolen phones stopped immediately (here in the UK mobile phone theft is a big issue and I was wondering why)?
• 3a) What mechanism do providers use to work out whether a phone has "payment" left to offer calls/web/texting?
• 3b) Do they just supply the service and work out the charges later?
• 3c) Can services be switched out individually?

Sorry for the random questions but I'm trying to come up with a project and needed to know if the groundwork was in place. Also apologies for the question numbers but thought it might help clarify any answers I might get. I am not an Android developer but I do design databases for a living so I should be able to cope with reasonably technical answers. I also wasn't really sure where to post my questions as it's not really specific to Android or any other OS.

Thanks for reading.

Mike

Anyone know if there is a more appropriate forum on the web I could ask on?
Many thanks
Mike