Two questions I couldn't get answered

So far today I've had two questions I wanted to find answers to, but neither the new MSN Search nor Google could help me.

Can anyone out there help?

1) Where did the phrase "Between you and me and the fence post" come from? (I know that it means something should be kept a secret)

2) How many miles of film did James Cameron go through while shooting "Titanic"? (I know it took about seven months)

Thanks!

P.S. James, if you're reading -- I LOVED the film! Call me and we'll do lunch.

P.P.S. I promise I have some "real" content on the way... it's just taking me some time to write it.