There is already a request for this feature. Please vote on it Option for semi-persistent automatic skip intro
As for the jumping forward:
while playback is in progress, press “OK” once.
This will bring up the player controls.
Now go “Up” once. This will move the focus onto the timeline.
Now use the “Right” and “Left” buttons to move rapidly on the timelime.
If you have enabled Video preview thumbs on your server, you will also see a small preview of the video picture on all positions. https://support.plex.tv/articles/202197528-video-preview-thumbnails/
