Regarding the "off of" with the redundant "of", I have been thinking about this and have realised that I would be guilty of this in spoken English but not in written English.

I'm not sure if it relates to my Northern English roots or my spell in the South as I can't quite hear the accent I would use to say "Will you get off of that wall!".

It is most likely a Northern usage as we are very fond of redundancies.

We are also rather fond of asking questions in the negative "Don't you like this dress?" means "Do you like this dress? A particular favourite is to throw in as many negatives as possible as in "weren't you thinking of not going down to the shops then?" meaning "are you going shopping?".