I was a longtime Stl commuter and I can second what flyguy81 said. ORD can be tough at times with weather and weight restricted flights. Trans States and Gojet also have crew bases on both ends so there can be multiple positive space crewmembers gumming up the works so to speak. Just leave yourself multiple backups and you can make it work.
As for 737 flying coming back into StL, I would not hold my breath. With the aforementioned regionals headquartered in St. Louis, I am sure they will fight tooth and nail to hold onto the flying they have. Anything is possible though. Heck, 15 years ago ALL StL UAL flying was mainline.
Good luck and welcome aboard!