
Based on those calculations, I'd just take 3 and 3/4 teaspoons and call it 5 grams. You'd be getting a bit more, but that won't hurt anything.
As far as taking it on non workout days, it's prob. not as necessary as it is pre and post workout, but would help aid in recovery. If you buy in a large enough quantity to make it economical, go ahead and do it.