Well you can tell the particular applications to open in Windowed mode and drag them to the particular display you wish to use. The Windows shortcut to move a window to the next display is Win+Shift+Right/Left
You can also change your primary display to the one which you'd like to play full screen applications on.
The more user friendly solution is to purchase or download an application which can manage dual displays a bit better than Window's native functions. Here's a list... Realtime Soft UltraMon DisplayFusion Actual Multiple Monitors MurGeeMon
As far as TF2 is concerned, you can use the launch commands "-noborder" and "-windowed". The first command will cause a windowed game not to show borders then second command simply forces the game to run in windowed mode. "-noborder" should force windowed mode.
To use these commands you can either append the commands to the end of the shortcut target line or you can add it to the launch options within the steam games window itself. Right Click Game > Properties > Launch Options