New to Sumps. Have a few questions.

[Slick Fork]

Definitely go find other people with tanks and have a look and a discussion about what they like and, as importantly, what they don't like about their sump set up.

A very important consideration is the amount of water in the return pump section of the sump. That's where you will see the water level fluctuate due to evaporation, if you don't have enough capacity in there you may lose the ability to leave the tank for a day or two without top-up. Evaporation that may seem insignificant against the size of the system as a whole may be enough to leave your return pump running bone-dry