You seem to be attempting to install and use many different media players to achieve particular things, but without a lot of success. Maybe some of the things you are trying to do are just not possible.
Windows Media Player - You want a video to "begin playing" in full screen mode.
Is there any reason you cannot use the "Full Screen" button on the WMP interface to switch between full screen and smaller screen? On my WMP version 9 it is a button bottom right hand side of the WMP player window.
Try this: In WMP, goto Tools > Options. Click the "Performance" tab. Find the "Advanced" button under Video Acceleration and click. In the new window, find and tick the "Enable full-screen mode switch", (there are two, so select both). Click OK, then Apply, then OK. If those options are already ticked, toggle them off and try that.
Another option: When the video starts playing, press the ALT and Enter keys together to change to full screen mode.
Apple would prefer users 'only' to use their own Quicktime player to play their .mov files. So some media players will not play them. However, some media players will play them if you open the media player, goto File > Open, navigate to the file and select it. VLC Player will open and play .mov files.
If you want a particular media player to automatically open when you double click on a .mov video file, then you need to "Associate" that type of file with that media player. Most players have options to do this in their Tools > Options. For example, VLC in Tools > Preferences, then the Interface tab, then "Association Setup" offers .mov if you select that and click Apply.
Or, right click the movie file you want to associate with a particular media player, select "Open with", and choose the player of your choice, (you may have to click Browse to find that player if it is not listed), and select the "Always use this program to open this type of file".
What happens when you try to play .wmv files? Any error messages? if so, perhaps the file itself is corrupted.
The same question about VLC. Those media files it cannot play. What error messages do you get?