Sorry if this has already been addressed, but I was wondering where Canva Pro images fall as far as using them for manips or layouts? It's possible to pull credits for elements and stock photos so if these elements are properly credited, are we good to use them?

Yup! I've been using Canva exclusively while my tablet has been broken. My understanding is that as long as you put in the work to give the proper credits then it's all good :) 

On the help page for crediting there is a section about Canva stock! Crediting Guide