You need a thermostat.

You don't need the light fixture, unless you're planning to watch your snake at night--then you can use a blue light bulb. I wouldn't leave it on all night, just turn it on when you want to watch the snake.

If you're using a tank with a screen top, you will probably have to cover most of the top with plastic anyhow, to hold in the humidity.

I wouldn't bother with the 'Repti-Bark'. It's a pointless and highly overpriced product, and it absolutely cannot be cleaned in the ludicrous fashion described on the package. Get aspen shavings, and change them frequently. Or just use newspaper.