Turn fullscreen to true in JLH.ini.
Try turning AutoDetectKitMonitors=true.
What is your screen res?
And resolution supported are in JLH too (1360x768, 1366x768, 1365x720, 1280x720, and 1600x900) maybe some more like 640x480 and 800x600, but highest possible is 1600x900 (without patching).
Then for game stuck in windows mode, try using DXwnd as i got it working with this, learn it (not difficult), try some tweaks, it should work.