Hope you join us Lava..
You will recieve back blocks of probably various sizes...I plan to open the envelopes and go down the row swapping blocks...so it should be a variety..just depends on what comes in.
There is no color scheme per se.....just funky...you will be able to tie them all together when you get them by using a consistant color sashing or another setting type block.
And yes...your finished size will be divisable by 3".....then plus the seam allowance...so 6" would be 6 1/2" if you were doing a square.