I assume that dropdown menu is CSS based with jQuery as the transition. You have set that 4px border to the bottom of the links at the top. You would need to add the same border to the top of the...
Haha. By giving an example wouldn't I just be doing it for you? check http://docs.jquery.com/Tutorials for tutorials using jQuery. It looks like you already have the relevant knowledge on the CSS...
In my view there are few ways to go about this. If the links are contained in seperate pages it is easy to highlight them differently, the other option would be to write some javascript to recognise...
I see no good reason to not use pixels for inches when defining some elements.
What is it you're applying a height/width to? I suppose that's the relevant question I need to ask... !
I would avoid inches personally. Pixels provides more accuracy however I'm not sure I fully understand what you mean with regards to cross-browser compatibility?