1) setup display tank on or near wall with a sideroom to store all equipment/sumps, etc so it is easily accessible
2) I think I would design a better way to do water changes. Maybe have 2 x 50G barrels - one is plumbed into the tank to act as additional water storage but plumb it so it can be bypassed. Have the second tank as fresh makeup saltwater fed by DI, etc filtering. This way you can enable the bypass on T1 without affecting the main display tank, drain T1, transfer fresh saltwater from T2 to T1, disable the bypass on T1 and your done. Wait for T2 to refill with DI and add salt and mix and do it again.
3) Make sure to have air exhaust from sump area and lighting area - this way you move a lot of heat and humidity out of the house