Hmm, OK. Does grouping ships within a fleet really work though? If fleet members maintain cohesion with the leader, what good does it do you to have subgroups? Just for ability control?
You can control sub-groups within a fleet regardless of the fact that they are in a fleet. Once they're done with whatever orders you give them, they will return to the leader. For example, let's say you have a simple fleet of a capital ship, 10 Cobalts, and 20 LRMs. You can give your fleet a move order close to the planet, so they blast some structures and then the capital ship starts bombarding. You can select the LRMs, and give them attack orders on the other side of the grav well and once they're done they'll return to the fleet's position on their own. This way, you have the overall fleet that doesn't need your babysitting to stay together, but you can still control each and every ship within the fleet.
So basically: if you give the whole fleet an order, it will execute based on the cohesion and engagement ranges. If you give ships within a fleet an order they will behave as if the fleet did not exist, following your orders and ignoring cohesion until they're done, at which point they'll fall back.
I can't see much of an alternative to using fleets, as the ability to instantly check fleet composition is vital and not possible with ctrl-groups alone. (Unless I'm missing something - is there a way to pin ctrl-groups to the empire tree or otherwise tell exactly what their constituent ships are without going to the search panel?)
Unfortunately no, it's not possible to pin control groups. For a while in beta there were no fleets and control groups were shown on the empire tree, but when fleets were added for the release, the control group display poofed.
Right, I get the general idea of cohesion, but in my case, as far as I can tell, fleets set to normal cohesion don't pursue enemies at all. It's not that the ships aren't all chasing down enemies willy-nilly; the entire fleet, leader and all, sits inert on the other side of the gravity well while my stuff is getting exploded.
I should try again and watch more closely, I guess. Maybe I was too impatient for anything to happen and jumped to a false conclusion.
Was the auto-attack range set to gravity well? Along with cohesion there are also settings for Gravity Well, Local Area, and Hold "attack stances", if you will. These determine how far ships will go to attack their targets. Now, within a fleet, this setting works in conjunction with cohesion. For example, if you set the fleet to Grav Well/Loose, the leader should be able to engage anything in the grav well, its followers will fly around and they'll be able to spread out a fair bit to chase/attack targets of opportunity. If you set the leader to Grav Well, but the followers to Hold, the followers should never leave the fleet leader and attack only what's in range of their position at all times. If you set the leader to Local Area, then the leader will only chase what's close to it, but not all over the grav well. From your description, it sounds like you had it set on Local Area.
I need to be able to check group composition so I can queue reinforcements and make other strategic decisions, easily add ships to a group, and give them general orders such as cohesion, group jump status, etc. In theory, it looks like fleets are meant to meet those needs (especially since control groups can't be pinned to the empire tree, while fleets are pinned by default).
I think you can achieve most of this if you start using a combination of control groups within a fleet, and alt+click. Because the fleet is pinned, you can always expand it and see its ships without it being selected. Which means, you can selet a control group within the fleet, and it will highlight only the ships belonging to that group within it. As you mentioned in your first post, indeed the upcoming patch makes it so that if there's a control group for the entire fleet, ships will automatically join that group and the fleet. However, they will not join any sub-group of the fleet automatically. So if you have a control group for your LRMs within a fleet, a new LRM frigate will not join it, even though it will join the fleet. This is where alt+click comes in - it select all ships in the gravity well of that type. So, when you have reinforcements coming in since they'll be added to the fleet automatically, you can alt+click on a ship stack/type in the empire tree and quickly update your control group.
Now, to be honest, I'm not sure if cohesion is whole fleet based, or if you can change it for a specific subgroup of the fleet - I have never tried. However, my gut tells me that this is possible, and it is definitely possible to set engagement ranges for specific subgroups of the fleet. This also becomes easier if you start making control groups within the fleet.
However, as it stands, ships are automatically joining my fleets, which basically defeats their entire purpose (i.e. controlling a specific group of ships). When I do get ships assigned to the fleet I want them in, then I have to reset all those general behaviors and my control-group assignment for the fleet. Ideally those kinds of behaviors could be set by default at the group level, precluding the need to re-assign them every time I add new ships (sounds like the upcoming patch may address this to some extent). Then, once everything is all set, I run into seemingly flaky auto-attack behavior.
Yes, the upcoming patch pretty much settles it. Now, ships joining the fleet assume the same settings as the fleet, so you will no longer need to update the settings constantly. The auto-join behavior doesn't change, other than also assigning the new ships to the overall fleet control group, but not having to update the settings each time is definitely a plus. Hopefully your auto-attack problems will be solved once you make sure that everything (or the leader, at least) stays on Gravity Well engagement range.
It does help, thanks. I appreciate it!
You're welcome 
