1. Well there's Ja++, which as I understand it is basically an enhanced Ja+ remake, that may have increased limits, but you'd have to ask @@Raz0r.
2. Skyboxes still work as they did in Quake 3; but what you have there is not a skybox shader, it's basically just a wall. But I still don't know what your issue is. And you're right, there's a slight difference in quality after all.
9. Length alone is not enough, you also need location, as evident in backhand sabers.