JoFo

It is not possible to get more than 4096 px per display port. You will need to split that screen over 2 display ports. Specs for Firepro W8100 Four discrete DisplayPort 1.2a outputs Maximum DisplayPort 1.2a resolution 4096x2160

I have been using the Presonus AudioBox 1818VSL with Watchout for several years. It works great for both Watchout 5 and 6. Very reliable. Watchout 5 required older drivers but Watchout 6 works great with the newest drivers. Be sure to use use USB2 port instead of USB3.