Sorry, I'm only aware of Georg writing a book/guide on PD7 in German.
http://www.video-intern.com/
Codec - a dll file created to compress or decompress a media file format into a different type of media file.
music audio files, .wav into an mp3
video, .avi into an .mpeg (mpeg2 DVD format)
Codec's aren't as obvious in PowerDirector. In programs I've used previously you would have multiple choice codecs to compress your video to. The downside is the viewers PC has to have the decompress (or same) codec on their system.
Ray, just stick with basics ... and ask questions. There are a lot of people who can answer you and many more who would appreciate you asking those same questions.
PiP = Picture in Picture - it's just a term used to describe a function here in PD (PowerDirector). A PiP is an overlayed image or video file placed by PD over what is in the main video timeline. A PiP can be stretched, changed and played with by using the various editing tools. The number of PiP's in PD7 is 6. With the higher numbered PiP being the dominant overlayed image.
Frame rates. The region/country you are in is either in a PAL or NTSC zone. PAL is 25fps and has a frame size of 720 x 576. In an NTSC region the frame rate is 29.97fps and the frame size is 720 x 480. In PD7 if you bring in a video with a differing frame rate a warning message appears. PD7 will compensate to a degree by either reducing or adding additional frames. This can have an effect on some video... so be careful.
I've simplified my explanation perhaps.... or maybe gone beyond what you wanted. Just ask ... and the forum should answer you.
Dafydd