About Free Collection. Should I turn on both buttons or just one?

Read the Free Collection FAQ before you decide.  Forever is a really long time. Over the life of an asset, it could earn royalty fees many times over which you'll never see. 

https://helpx.adobe.com/stock/contributor/help/free-collection-contributor-information.html

I clicked both.

I would suggest clicking on both, as it might improve your chances of having more images selected, but that's just a guess. Don't overthink it, because Adobe only selects a very small percentage of nominated assets for the Free Collection anyway.

Either or. It's up to you.