MLB clubs have until midnight on August 15th to sign high school kids. After that date passes, they are good to go.
I know nothing on Woodruff, what little I have heard on Lindgren is that he and MSU were surprised it was the 12th round, and the Cubs will go overslot to get him. They aren't going to throw out 7 figures, but they could throw out 250K+ which will make anyone think twice.