I might be wrong, but it is my understanding that a lot of these warnings deal with undefined or implementation defined behavior and that behavior is changing this release. If that understanding is close, for even some of these, then just suppressing the warnings means the software will behave differently.

My understanding is that these were all existing warnings that were off by default (you needed to pass -Wall to see) that are now displayed by default; I don't see any indication in the patch thread that there were corresponding behavior changes.

Nah, you can override the flags and still will remain working, but you have to be aware of it and figure out how to change the flags of a project properly.