VERY IMPORTANT: you should *not* plug a mic directly into the Eventide! The inputs are not designed to handle mic levels. A mic preamp should be used to get the correct impedance matching and it will also sound much, much better.
You are using the H8000Fw as an audio interface, converting analog to digital. which is a possible use for the H8000FW. If you have a dedicated audio interface you could also use it, as it very likely has a mic preamp dedicated input. If you don't have an audio interface for your computer, than you need a mic preamp to connect the mic to the Eventide.
You will need to modify your H8000 internal routing to directly connect the analog input to the FireWire channel feeding logic, bypassing the DSPs, for dry sound. The problem here may be that you are using the H8000 before the pluging AND would like to use it after them as well. This, if possible, requires careful tweaking of the H8000 internal routing and considerations about the routing possibilities in Logic.
Regarding Logic questions, we do not support DAW software as they are simply too many and different to do so. Dedicated forums are available on the internet for this.
In my opinion the best way to use your gear would be:
mic > dedicated computer audio interface w/mic input/preamp > computer
H8000FW connected via FW to the computer, using Logic channels Send/Returns to feed dry signal to it for FX and then back to Logic.