Is using 16 columns OK I have a sight where I require the sight to have the right hand quarter to used for ads, pis etc. and the rest for my main content which is often split to 2 I.e. 6+6+4 cols. If so how do you get the 16 cols. Total width would be the regular 1200 pixels. Am I complicating things?

On the layout tab at the bottom you can set your column count.

Nop, that's totally feasible. Most common are 12 or 24 cols since you can divide those by 3 and 4. But if a specific project works better with 16 columns there's nothing wrong with that