Linking back to the freewrite is easy. You just copy the link and say something at the end like
this is a freewrite based on this prompt: https://steempeak.com/freewrite/@mariannewest/day-726-5-minute-freewrite-wednesday-prompt-humming-bird-flower
As far as citing your photos - you want to do that in all your posts. Otherwise, you can get in trouble with Steemcleaners among others.
You can create a footer saying something like
"All photos are my own unless otherwise cited" Something like this. You can create your own footer on something like canva (free program)
or write it every time
Or have something written up and copy it at the end of your post.
Hope that helps