ImageMagick batch file conversion help needed please.

Running KDE desktop and ImageMagick (IM) built from source with libfpx library included as delegate. (fpx conversion no longer readily available hence the delegate for conversion)
On reviewing my picture library I have found that in the past I have run conversions from fpx to jpg on the same files at different times and the results have not been consistent in resolution or with metadata, probably because I used different conversion software.
What I wish to do to to go back to my source fpx library data and convert again using IM but there are two criteria I need to include.
I wish to be sure I get the “best” image available from the original fpx image. I know “best” is sometimes used in audio applications but how do I achieve this in IM?
The second concern is to ensure all the metadata in the original fpx pictures is transferred to the jpg image. I found that on some converted files there was no metadata!
Finally I probably need help with the batch file syntax.
If anybody has any advice on these questions please let me know.

It’s a bit discouraging to use imagemagick though it’s a powerful tool.
Have you tried to look at gimp-bim-plugin for batch processing of image file?
It is in the multimedia repositories.

For batch image resizing you can try BIR,
It is in the graphics repositories.

Those are all gui tools which maybe easier and user friendly.