Best Method for transferring from MacBook Pro to MacBook Air

Migration is the only way. You can run it when you initially set up the new Mac, or after using the Migration Assistant app. If you choose after setup, don’t create the first user name the same as the one you’ll migrate. Migration works best if it creates that account, not try to merge.

if there are any errors on my current Mac will those errors be carried over?

Probably depends on the source of the errors.

There is no other way of moving those Libraries, complete with all the metadata you want.

You can copy the entire package over, but that would certainly carry over any issues.

The metadata (e.g. play counts) is stored in a file in the Library and is based on the storage structure. Copying that file alone will not restore the play counts because they don’t store the play count for “Mary had a little lamb.mp3”. It stores them play count for something like ASC6D-IJWER-NP0S4-SOKE8W0SK-SERTHO.

When you just copy the media file, and the index, it may not be able to associate that new file with the index reference.

The Photos are in a package in your Pictures folder, Photos Library.photoslibrary.

Since you have been through so many upgrades, the music is probably in the old iTunes structure. The location of the files will be listed in the Music app Preferences. The metadata is in the Music Library.XML. That file is probably one level up rom the files.