New to the snake world!

So i plan on getting a corn snake, it will be my first tank! So I figured ide come here and get more information on everything before I just go and get one.

I plan on housing him in either a 65 or 75 gallon tank. ( have both laying around in my shed)
Are those too big or bigger the better??

Im ok on substrate and decor. My next question would be about lighting. I've had a bearded dragon for about 10 years, and I know they require alot more lightning then snakes or corn snakes.

So for lightning do people recommend having a light on top of the tank on the hot side and ALSO a heating pad underneath the substrate? And if so does the heating pad stay on 24/7 or turn off when I turn off the heat lamp at night? Do you suggest putting thier hidding spot on top of where the heating pad is?

As for humidity? I read conflicting things from 50% all the way up to 80% so I'm wondering what everyone else does? And how do they keep thier humidity? Just spray the substrate and monitor the readings?