Wow---Quite a mis-match.
AVI is just a container, the video files are Mpeg4
The first is Ntsc 29fps 16:9 ratio
2nd is Pal 25fps again 16:9 ratio
3rd is Pal 25 fps but 4:3 ratio
4th Mpeg 1 is Ntsc 29fps 4:3 ratio
5th Mpeg1 is Pal 25fps 4:3 ratio.
The Mpeg2 video is standard Pal for burning a DVD, up to 60 minutes of video.
and yes editing the Mpeg 2 will be easier than the Mpeg4 types.
Has using Mpeg2 types cured the problems?
MP3 song files may give problems, and has caused problems for some users.
Convert the mp3 clips to Wav.
Viewing these video properties I don’t see much in the way of quality, all are using a small frame size.
Mixing 4:3 with 16:9, you either use a picture in picture approach, or some video clips are stretch/distorted to fill the frame?
Mixing Pal and Ntsc will cause some flicker when converting one to the other.
Batch convert is probably the best solution, if you have a lot of editing to do then consider converting to DV-Avi:-
Microsoft AVI files
24 bits, 720 x 576, 4:3, 25 fps
DV Video Encoder -- type 1
A better format for editing, but 13 Gb per hour.
By the way, I know you may have said but what are you trying to make, a DVD or video for the internet, maybe YouTube?
and is the final video gonna be Pal or Ntsc?
Finally Mpeg4’s require quicktime, updating your player to the latest version may help.
Just to contradict myself, some video studio crashes has been cured by reverting to an earlier version.
X4 provides QT 7.5.5