I'm fairly new to the game, bought it with the AM kickstarter, but given the discussion I thought I'd throw in my PoV on the subject at hand, given I've played in and managed professional and non professional clans of various size.
1.) Ranks - There should be some sort of counter for the ranks and how to progress in the game.
The "Progress" is well explained and detailed in the "Progress" tab, with each class having its own paths. The multi-progress, opposed to a streamlined one like you suggest, is even more optimal, because it doesn't force the player to stick with doing one thing and one thing only, potentially ruining his own team and crew. And if anybody has ever leveled up classes in, say, Modern Warfare, will perfectly know what that does mean in a cooperative environment.
2.) Player Scores - This is obviously calculated by kill shots, assist shots, and rated by the most important work from their particular occupation they've done (ie: An engineer repairs a broken engine +2, repair hull +1, etc.) based on its importance.
This brings a serious problem to the philosophy of this game. You don't count, anyone doesn't count, only your team does. You only win if your team wins, not if you have more points than anyone else combined. This is why, imo, they planned to not show which crew has taken what points. What if players then start, just like they always do in typical multiplayer games, to do what they think is best to achieve the "best score" in the game instead of winning? Ever played FPS? How many times you've seen, during a strategy type match, the player with the top score calling his team names because they "couldn't keep up" with his greatness? I did, one too many times.
4.) Leaderboards - These are the most legendary way for players to compete as the best in games. It adds a level of competition while not getting in the way of the casual playing experience of other players.
This is the best way to utterly destroy the game. Time and time again it has been shown that public leaderboards with names bring nothing but grief to the general gameplay. Generally speaking, the first thing that popup on leaderboards are hackers, be it the top FPS of the time or that crappy game on facebook. All the time, all the year around.
Secondly it just does not fit a game meant to be cooperative in nature. What good does being the top player on a leaderboard if your team constantly loses because instead of the "killing" you should have done the "repairing" but you just needed that one more kill that... well, you've got the point.
If need be, there's another type of leaderboards that do not have these problems, and is the histogram one, where you "compete" (privately) against a pool of results. But you, and only you, can know if you have done better or worse than other players. Put names anywhere on a list and players will go crazy fighting, even using every single glitch of the game to receive the "gratification" of the top positions.
What if there were additional slots of 3, 2 and 1-man ships all with their own roles?
IMVHO, Guns of Icarus is not, and should never be, a lone wolf game. Aside the fact I can't even conceive a ship with less than 3 players, how would the "1-man" ship go around, repair itself and do damage?
To the contrary, although I do not know if feasible, I would like the opposite. Huge flying giants of 6-8 players each, but again not to be mixed with 4 players ones. Because a different crew size composition can make or break the game dynamics.
I should add that I also do not like the path a lot of FPS games took/are taking. Being of the cooperative type I feel pity when players start doing silly things because they "have to level up skills" instead of, say, capturing flags. And the balance and philosophy of GoI are what really struck me. Bringing it to the path of demise seems stupid. And sad. Very sad.
My 5 cents.
