I am the creator of most of the Eventide presets/algorithms in the H8000.
Talking about FoH apps:
the main concept is that no matter which audio format(s) you will be using, the unit has 8 physical I/Os from/to the external world. The 2 DSPs can run 2 presets at the same time and have 8 software I/Os. These 16 outputs can be summed at output stage but mixing will be necessary internally. So most people may end up using the H8000 as 2 parallel routed machines, running 4 mono FX or 2 stereo ones or combos of them in each DSP. It's also possible to run 4 stereo FX in each DSP but you'll have to sum outputs internally (ROUTING) and set levels inside the Eventide.
There are presets written with FoH in mind:
Bank 16 is actually named Front of the House. It contains many mono/stereo/multi stereo presets, like 4 verbs in a single preset and many other popular fx.
Bank 32 Multiple Machines has a terrific variety of 4 to 8 I/Os mono/stereo/combos FX, from 4 mono compressors>EQ+ 2 Stereo Vintage Delays to Stereo BandDelays+Filtered Dlys+Ducked Vintage Dlys to Diatonic Shift+delays+reverb to MicroPitch+Pcm70 style verb+Pan Dly. The presets manual has all the info about these terrific tools.
Even the mighty MIDI Virtual Racks in the last banks can provide a lot of functionality to FoH, being presets with 5 processors in each and 10 storable tweaks that can be recalled manually or via a single MID CC message.
The typical use would be connecting the H8000FW so that your mixing board Aux Sends will interface with the Eventide for Send/Return audio to FX and back, as you perfectly know in your work.
Please don't hesitate to ask any specific question you might have.
all the best