Fan ducts through attic

[Kafer]

I'm looking for tips on running a duct through an attic. For reference, please see here on the issue I am experiencing. In short, I have spent a bunch of time and money trying to properly vent a range hood fan and bathroom fan through the roof without it leaking back into the house.

I'm going to try attempting to vent out of the soffit area, but unsure on how to do this. My plan is to run an insulated duct in between the ceiling joists to the soffit area. Is it ok "raise" the duct up and over the beam running along the edge of the attic? I'm worried that it may condensate and water may pool up in this area.

Any tips or tricks on how to install a soffit vent? I was thinking of going into the attic, and sticking a pencil through the soffit (if I can fit my arm in there), then going outside and cutting a hole and installing the vent.

Hoping someone can offer some advice... thanks in advance!