Although version 11 works pretty well with a variety of video formats, this is really a mess of a video mix, and there are no guarantees with the results. Especially because some of the video is high-rez and some of it is standard definition -- and some is even lower resolution. So know going into it that, at the very least, your 640x480 and especially your 480x352 video is going to look pretty bad when you blow it up to 960x540.
How do you plan to use your output video? Online? On YouTube? On a DVD or BluRay? on an iPad? There may be a more optimal output format.
There are also no guarantees with the MJPEG video you're using. Sometimes it works and produces mediocre results -- and sometimes it doesn't work at all.
That said, I'd open a new project and select the option on the New Project screen to force it to standard definition DV widescreen.
Then, before I put too much work into it, I'd add a sample of each movie source to your timeline and use Publish & Share/Computer/AVCHD with the YoutTube Widescreen SD preset to output the video to see if you're happy with the results. No point in putting days of work into this project if it's ultimately not going to work.
Indeed it is a mess of a mix. I am happy with this mess, because these are videos from my firstborn grandson, shortly 1 year of age. They are taken by various persons each bringing his or her own device. The output video is for usage inside the home: such as the screen of a TV, PC, Laptop, Tablet or Smartphone. All these videos contain nice content. Quality is not important, the possibility to include any of the formats is.
Steve, I will follow your suggestions and will post the result.