Can I travel within Thailand while my non O marriage visa is under consideration and do I need to file a new TM30?

Get in the habit of doing your TM30s online then each time you return it's a simple case of resubmiting your details

Shouldn't have a problem traveling while on the under consideration stamp. Does your immigration office usually do home visits for your yearly extensions? They usually tell you when you apply if they're going to do one or not.

Now as far as whether you have to file a new TM30, that's between you and your immigration office. The way different offices do it is all over the place. You'll have to ask them how they enforce the TM30 rules at your office