A couple of changes I'd like to make
 

I could just stat hacking away it at, but I feel it would take me longer than first asking where and what to change to get the result I want.

Firstly, I would like to make the aggro number on the hate bar much bigger, increase the bottom aggro bar size for the pet and ad a second number for the pet hate as well, on the right side of the bar.

Also wanting to increase the HP% in the target window, and perhaps removing the level, it's not really needed for raiding. Which would give the extra space needed for the increased HP size.

Also I would like to create, or split the two bottom bars up, so I can have one on the top of my screen as well as the bottom.

I already modified the Icon Size stuff so that's already been taken care of :P

If you copy the eq2ui.xml from default into your customUI or DrumsUI folder, you can open that with the UIBuilder.

Most of your tweaks to sizes are going to require you to resize the parent element in which they reside.
So if you wanted to simply increase the hate number sizes, you'd need to change the font style, and then increase the window size so that it actually displays properly.

Same thing for the target window.

Pet had you can probably copy from pet window and resize accordingly in the threat window. If you're using my window as a base, there may be some code tweaks to properly hide/show the bars depending.



As for splitting up the Stat bar, there's no great way for me to do this without stripping code out of the original and making a secondary window that essentially does the same thing.

The problem is that I hate variants, and I'd have to change the code a bit to support each version separately -- something I don't have the desire/extra time to do myself.
I thought someone at some point made their own separate stat bar mod using mine, but maybe not.