Copying

(Edit > Copy) as usual
You can copy conditional formatting using the Format Painter
Paste Special - select "Formats" will paste the conditional formatting

If you copy a cell and paste it over a cell that has Conditional Formatting applied to it then the formatting rules will be lost without a prompt.
If you delete or overtype a cell with conditional formatting it will be lost.
Sometimes when entering formulas excel will try and put quotation marks around the formulas after you press OK.
This is because excel sometimes thinks it recognises text instead of a formula