If you do ALT-O when you are in the game, you get the game settings. In there (in display I think) you can change the resolution of the game. If you set that to your screen resolution, you should get something that fills most of the screen.
Seeing as it's windowed, I don't think you can ever get rid of the window bar at the top. But if you press the windows key or alt tab until you get your mouse cursor outside of the game window, you can click on the bar at the top and drag the game window until it fills the whole screen, with just a little bit of the bar at the top showing. So it's almost like having full screen. Once it's like that, I personally then like to right click my windows taskbar, and set it to auto hide, and tell it to dock at the top of the screen. That way it's completely out of the way when I play the game and the game is as close to full screen as it gets.
I know that it's also possible to edit an ini file (I forgot which one) to tell the window exactly where to go, rather than doing the windows key / alt tab thing and dragging it yourself. As for the Luclin UI, I don't know anything about that sorry. Hopefully someone else can help. But I do know that there are lots of custom UI's out there that people use with this game.
