First part next: Let's assume you have your guitar plugged into the FF instrument input and the H8000 connected via ADAT 1. In the FF Matrix, all of the 24 FF inputs show up as the rows and all of the outputs show up as the columns. To connect an input to an an output you click in the box at the intersection of the input row and the output column.
To send the guitar to the H8000, you connect the Guitar row with the output column for the first ADAT channel (out 13).
In the FF Mixer, you should see the guitar input signal in the first mixer channel in the top row when you play the guitar. When you send that input to the H8000, you'll see mixer channel 13 at the bottom of the mixer (third row) show activity too. If your H8000 is producing output, you'll see that show up in mixer channel 13 on the first row. (The second row has the return from your DAW software, via the firewire link to your PC.)
To listen, plug in headphones to the FF, and use the Matrix to assign an input to the headphones: Channel 1 to listen to your raw guitar, or the first ADAT channel (13) to listen the sound after it's been processed by the H8000.
You don't have to do anything to send the inputs to your DAW; all inputs go up the firewire link (this is configurable in the fireface settings application). But to connect a return from your software to a FF output you have to use the matrix to set it up.
If you want to mic your amp instead, you do the same thing I've described above…just use the microphone input ( I use in 7-10 on the front panel) instead of the instrument input (in 1).
