During Early Access it's best if you post your suggestions on this forum or the Steam Aerofly FS 2 forum (there is a specific sub-forum on there for suggestions). As for making modifications, what are you aiming to do? I'm a moderator and work directly with the ipacs team, also Jan (Jet-Pack) works directly with the team as well. I would rather see the FS 2 community respond to what you wish to do prior to discussing it with the devs directly, anything well received goes directly to them for consideration.
Jeff