Import Contributions - Update Existing without required fields

When importing contributions that will update existing contributions, it seems unnecessary to require Total Amount and Financial Type fields to be part of the import file when a user just wants to change/add information in a non-significant field.

It would also make for a better UX if on the "Upload Data (step 1 of 4)" page if the fields required in the uploaded file would be listed so the user can prepare the file accordingly before uploading, mapping fields, and then getting an error message. (This could also be said of Import Contacts.)