There is no difference. Your certificates are your certificates, it doesn't matter if you get them at "Bob's flight school" or "WalMart University of flight". All a potential employer cares about is you have the licenses. You already have a degree, don't waste your money on another one.

You have a great job, stay put. Get your ratings on the side and once you are finished with that, find a place to instruct locally (probably the place you got your ratings) on the weekends or when you aren't at LM, and then decide if you want to make the full-time plunge.

Being a LM employee, keep your eye out for additional positions within the company, test pilot, corporate, etc, might all be options for you to transfer to once you get your ratings and a few hours.