I havent read the posts in response, but to the op:
1. The map already does this to the best extent, which adds a layer of skill involved with coordination that I enjoy. Tactics like you suggest do happen, but in pubby matches its not common since rarely do two three captains who don't know each other communicate on that level.
2. I think its the wrong fix for a problem with people joining 5 seconds before the match starts, and you're hosed. Something should be done about that, though within lobby, not in-match. For joining in on a ship already in-match, look at its loadout, and take the what fits. If the captain really wants you to, changing loadouts is simple to do. Joining as the wrong class, I mean, if you look at the ship before you join, im not sure how you manage that. The current way to swap class after joining is hard, and time consuming, but possible, which is how it should be for the sake of exploiting.
3. Makes sense. If some can already do it, why not all? If its an intended balance mechanic, then ok. I worry itll be like the current hold-to-repair is though, and end up being less effective anyway.
4. Coming from someone who misses the old blueprint loadout screens, I think the screen is already busy enough. If such a thing were to be added, it should be toggle-able for each gun, so you can not just clutter the screen with cones. This would also require a top-down view of the boat.