Few questions about interface of vlc player

[nagato]

Welcome
I'm new here and I would like to ask couple of questions about that player.
1) Where to set amount of senonds that movie will be rewind when using rewind shortcuts
2) Can you turn off play/pause icon in the top right corner of the screen (when at fullscreen) when you pause movie
3) Can you turn off showing always on the fullscreen menu under the cursor when you move a mouse
4) Cam you modify shape of menu on the fullscreen like presented below

image

If image wont work , here's a copy of the link
http://img703.imageshack.us/i/91302517.jpg
PS
Could you use a screen showing positions of options you are talking about, english is my second language and my vlc don't have english interface so finding those options would be more easy for me that way

[NesteaZen]

Most of the stuff is in
Preferences> Interface> Main interfaces> Qt

[nagato]

Another quetion, can I set codecs that are not build into vlc player (installed on the os) to be used instead of build-in ones ?

[Jean-Baptiste Kempf]

No.

[nagato]

Another question, can I optimize vlc player for smoother playback of .mkv videos (sometimes they slow down a bit) are there maybe some guides for that ?

[Jean-Baptiste Kempf]

Another question, can I optimize vlc player for smoother playback of .mkv videos (sometimes they slow down a bit) are there maybe some guides for that ?

Yes, use GPU decoding or deactivate loop filtering in preferences.