You can stay UNTILL 22ND AUG , that's what the stamp means. Its's just a WAY OF SAYING that any further exrension after yr 30 days extn is NOT ALLOWED and hence 7 days GRACE PERIOD is given to pack your paraphernalia and get out.
An Ed visa CANNOT be converted to Non B visa. Cancel yr Ed visa first by a letter from the school , get out of Thailand . Then you can apply for your 90 days Non B anywhere outside Thailand with the help of papers from yr employer.
Yea right , I had hidden mine in various pockets of my bag and in my wallet so that I don't have to declare in my home country. I knew Thailand wouldn't give a shit even if it was 10k plus.