Is there a way to know what the most requested stock photos and footage is for Adobe Stock? Also, is it easy to setup an account to submit photos and footage?
The best thing to do is do searches for things your photography style or images fit in and see how many results there is. There is no way to know the actual search analytics as to what is searched for most.
Right now to become a distributor it is all done through Fotolia.com. Simply create an account there and add your photos for approval. There is a Stock Contributor Portal announced but no date has been publicly announced as of yet.