Simple Questions On Record Keeping Of Offences.

Some simple questions...

Let's say a traffic conviction stays on an insurance company's records for 3 years... when does the 3 year time start? At date of offence, or date of conviction (which can be many months after date of offence)?

If you are found not guilty at your trial, is there still a record of it somewhere or does it disappear forever? Basically wondering if a police officer can still see it on his in-car computer.

And what's the difference between a police officer and a police constable? If they're the same thing do they have a preference on how to be addressed?

Bonus Question:

During a trip in Mexico we got pulled over, my friend (who lives there) offered to bake the officer a cake if he lets her off. The next day we returned to the exact same spot at the same time and she handed him a chocolate cake. Everyone lived happily ever after.

Do you suggest I use this tactic next time I get pulled over? I doubt it's been tried here before - and I make a mean New York cheesecake! LOL

Thanks!