help on my website for soft or api or scrapp

Hello, i need help for two projects, please say me if you're able to do it :
1/ i have a shopify website, i need to send an automatic email to customer immédiatly when i put the tag "PRO" on the account

2/ my supplier is https://www.setterbakio.com/

i need you to create a way to scroll all the website, and make a list of the SKU that are out of stock, and to compare to the previous scroll to check if SKU are back in stock, or if new SKU became out of stock

for exemple :
https://www.setterbakio.com/cabezales-ibanez-acero
on this page A20942 is out of stock
A20941 is in stock

i hope all is clear and easy to understand,

i wait for your news and quote

thanks