Make one of your HSTs and measure it before you cut too much fabric. I'd be surprised by the time it's squared if it's 9 1/2". Mine would be a little smaller.
With the 9 patch, you need to add an inch to the 9 1/2 for two seams, which is 10 1/2, the divide that by 3 for the size of the block. Same with the rail fence. 3 1/2" blocks will end up 9 1/2" as will 3 1/2" strips for the fence.