well for the loading, 3d games and such can take quite a while to load and can sometimes just be naturally more buggy and glitchy in the browser version, I would recommend you download a build for it to work closest to how it was intended.. Otherwise the "press any key" thing seems to be working just fine for me on both browser and Windows build. I would probably just try the build if it continues to not work, but if your system is pretty old, that might be a part of the problem...
Oh, but an actual weird bug with the "press any key" is that in any other instance of it except for the intro, spacebar and enter wont work (the game will think you are entering back)
sorry for the technical problems, but let me know if this helped