FOV can be changed in-game at the Graphic options. All it does (to me) is just "push you futher back" into the cockpit so you see more of your cockpit.
It works the same way whether you edit the file or use the in-game option.
Narrower FOV can lead to motion sickness, which is the exact opposite of what you want in a video game. Some folks have reported motion sickness playing ED, and that's a huge shame, since it's one of the gentler first-person view games out these days. Even so, increasing FOV ought to help.
...Turn off head-bob...
...Have a target reticle in the center of the screen...
Definitely narrow FOV contributes to motion sickness. You can look it up for yourself (which is a good idea for budding skeptics) or you can trust me (not the best idea, but certainly the quickest) since I get sick in a number of games now. It doesn't help as you get older, unless you and your dad are somehow uncomfortably close in age. And it gets worse: often enough the trait is passed on through genetics! But you can also get it through concussions or a really thorough case of the flu. Fun!
For your dad:
Play as far away from the screen as possible.
Sit in a brightly-lit room.
Open up the FOV as far as is comfortable - too much fisheye won't make you sick, but it does look strange.
Turn off head-bob
Things that also help:
Play in a letterboxed screen resolution as up and down sensitivity is stronger than side to side
Have a target reticle in the center of the screen. If that's not possible (it is in ED), make one out of a tiny piece of tape.
In regards to this, there is an option under controls I believe, where you can turn on something called a mouse widget. If memory serves me right, it adds a small dot at the center of the screen.The target reticle, you get with weapons out, which is not friendly. The tape can help, though.