KDP Book Cover Size Adjustment

I need assistance with adjusting the size of my KDP book cover. The primary requirement is to ensure that the cover meets Kindle Direct Publishing's specifications. While I am somewhat familiar with the guidelines, I would appreciate expert help to ensure compliance.

I have two projects but the current one involves taking the pdf file for my existing book cover that was successfully uploaded in KDP and now:

1) the total number of pages has significantly changed for this revision,

2) decided to change the interior paper from cream to white.

3) must be able to be successfully uploaded into KPD

4) original cover was prepared in photoshop but it is my understanding that photoshop will accept pdf and can make these necessary changes and then save as new pdf for uploading into KPD