Resizing rocketdock is inside of the "Dock Settings".
You also definitely want to use the Stack Docklet (found on their site or google)
To remove it when you're using applications (fullscreen apps?) it should be automatically doing this, otherwise go to Settings->Position->Layering->Normal
I prefer Always On Top and leaving it Hidden, it should detect and hide for fullscreen apps, never had problems with it.
I personally stopped using Rocketdock along time ago and would highly suggest XWindowsDock, works great, native-ly deals with stacks, has great STACK MODUS (MSPA joke), deals great with icons among other things, and works with literally any form of Windows from XP (prior to, but who uses anything else?) up to 7, and works 64 bit.
Another thing you definitely want to try out if not keep is Rain-meter, which you might be using already? It basically makes your desktop interactive and has some godly skins on it, can keep track of themes, and with a plugin can also have different themes for different monitor resolutions (So you can have it change with your resolution if you plug in several monitors or change resolution often), also has NO problem with old fullscreen games that like to change resolution without asking.
My desktop before Rainmeter/X Windows Dock got icons put on it:
http://pyrofyr.com/random/hs/NDesk1.png
After XWindowsDock got icons:
http://pyrofyr.com/random/hs/ODesk1.jpg
After XWindowsDock and RainMeter :
http://pyrofyr.com/random/hs/PDesk1.jpg