It's nice to see some new contributions to the forum.
The general statement that addresses most points is,they've been or they're being addressed. I'd look back in the forum to find out more behind each thing you've suggested.
The problem with adding this much depth particularly for personal ranks is that it would actually be taking away realism from players that don't have these assets in their setup. It conflicts with the rather simple nature of the game and makes it much more difficult for those to progress easily. You can complicate things naturally in the game by sticking to realistic vehicle allocations and such, but these limitation shouldn't be applied to how others play the game.
Combination units and PD supervisors have their own thread.
Apologies on the repetitive content. Still figuring out how to navigate through the whole forum! But the rank structure would not have to be a mandatory for everyone. I would treat it with the same mindset of the Quint. The ability for those who wish to use it is there but not mandatory when purchasing apparatus.
I like some of these suggestions as well but like in the previous post some of these ideas and combination units have been mentioned before. I like the idea of ranks as well but for players that have multiple stations it would take quite a long time to put these ranks in and if there were officer or driver classes that would definitely take a long time as well. From a realistic standpoint I would love to have this but from a game standpoint it would most likely take quite a long time to get all this in order. Had this been developed at the start of the game then I would have no problem.
Hazmat Rescue has been brought up before but because it's a combination unit I guess the DEV feels it would be too easy but who knows maybe later on down the line things will change. Same with the Pumper Tanker which has definitely been a huge topic discussed as long as I can remember. Technical Rescue is unit that was being considered for development but I'm not sure when or if that is being worked on at this present moment. PD Supervisor is an idea and idk what a Rehab Unit is. To me that sounds like Cascade.
You bring up a fair point with the timeline process. I would not make it a mandatory necessity of the game but rather an option for those who choose to be as realistic as the game lets them. Essentially the same logic as the Quint in game. An option but not a requirement to play the game properly.
I have read a few posts about combination units and don't see the "make it easier" view from the Dev & others. If that was the case, there wouldn't be any combination units to begin with (Quint, Dive Rescue can act as a Heavy). All combo units are basically an option but it is not mandatory to play the game. In result, there would be a wide variety of players who use them, don't have the ability to use them, or don't care for them. I have the mindset of giving players the maximum amount of options possible and let them choose how they play the game. As for the Rehab unit, this link can phrase better than I can: Rehab Article