Dragonsteel you have to go to the library in person for, aether there should be a thread in unpublished books, and for white sand prose you have to email Brandon. Any other unreleased works are either unavailable or on Brandon’s site.
In regards to Scandrian Magic, just go ahead and post your thoughts any way. If you’re really concerned, the coppermind (coppermind.net) likely has most of not all of the info you seek.
Of SA what’s your favorite book and Would you like a cookie?