It's typically easier for a snake to swallow head first, but that's it. There are no negative concequences for downing it a different way.

Do you have a thermostat, lamp dimmer or rheostat on that heat pad? Without one it will probably burn your snake, and you shouldn't need the combination of both the pad and the light, just the pad should suffice.
As for humidity, taking away that light will help from drying things up. A sterilite container or some type of vision cage is much more suitible for holding it humidity than a glass cage with a screen top. Those cages are only good for reptiles with low humidity requirements. For now, trying covering up most of the screen with foil or a towel to help hold the humidity in.