Honestly, I'd much rather the lead character be Stewart than Jordan. Rayner wouldn't be too bad, but I'd still rather have Stewart. And I'm pretty sure almost no one like Guy Gardner. But yes, they definitely need the right actor to play Stewart.
I heard a rumor that the next JL movie wont be for at least 5 years, which would be a great move for the DCEU. I don't know what truth there is in these rumors, but from the looks of the DCEU right now (Flash still having problems, and Batman just now starting to get things figured out), it seems like a pretty realistic rumor. I would be fine if the only other movies the DCEU kept making were WW and Aquaman. Shazam looks pretty good, but we'll see. I love GL, but I don't want a GL movie to be a flop (like the last one was).
I am with you on this point. I would prefer a Stewart Lantern movie over a Jordan one.