I'm faaaar from an expert, but I can tell you what clipless did for me, which may or may not help regarding trying to keep your foot straight when you pedal.

Once I had the clips set where I needed them, it was fantastic. I did a lot better at keeping my right foot straight - I have a tendency to turn it inward and use the blade of the foot for some reason. I also used to always have numbness in my feet after ~20 miles, and right ankle trouble (probably from the inward turning issue).

I have a lot more power now. It's really nice to be able to really use the upstroke, something I never managed with toe cages. I'm using the basic Shimano's, no issues clipping in/out, I can change the tension so it's easier/harder to clip in/out without too much trouble. Even with the tension at the lowest level, I've never "accidentally unclipped" while riding.