I did something similar when I upgraded to an annual pass this past summer. I had purchased 10 day park hopper tickets and memory maker and then upgraded the tickets to an annual pass in the park. While the cost of the tickets were applied to the annual pass, the memory maker wasn’t, but the amount was refunded to a gift card as I had used a gift card to make the initial purchase. If you read the fine print, memory maker is not refundable, so I was expecting to just eat that cost or transfer memory maker to my sister for her family’s trip, so I was pleasantly surprised when the cast member refunded me the cost of memory maker. Seeing that your friend was the one to purchase memory maker it’s likely that she will not be able to get it refunded, but she might be able to save the purchase for a future trip as long as she doesn’t activate (download any of the photos to her account) during the 30 days of memory maker being active and the 45 day window following the trip where the photos are still available. If you go to guest services in the park with your friend, they might refund the memory maker, but I wouldn’t count on it. More detailed information regarding memory maker can be found here https://mydisneyphotopass.disney.go.com/help-and-support/policies#1
I will add one thing though, while the website states that the photos taken during a park visit expire 60 days after that visit, when I accessed the photopass website after getting my annual pass, I was able to have access to photos from friends that were taken last December, so definitely pass the 60 day mark, I suspect the photos for annual pass holders are subject to different policies.
As for your second question, yes there is a fairly simple website with the dining and merchandise discounts located here: https://disneyworld.disney.go.com/passholder-program/passholder-benefits-and-discounts/
Hope this helps!