1) The base management system is is either completely gone or not implemented properly. For example many ground maps in ICW don't even show a clear picture when displaying the base layouts. Some even show a picture of Petroglyph. There are some maps that do display the layout but those aren't very common. I understand why this feature is usually not optimized, new planets and I've heard this feature is one the hardest to implement for the new planets and new maps for the previously existing planets. I would like the see a feature like this for the layout of the defense platforms in space battles, it's probably not possible but one can dream.
The game is finnicky with this stuff; we had it all in before, but then certain bits of it broke as it was moved around and we never got to fixing it. It is on the list of things we're trying to get done (plus there was a UI issue covering it for a while and we couldn't figure out what it was for a long time, stopping us from making progress on that front). As far as the pictures themselves, the previews and base setup images are actually extracted from something generated within the map editor, so we really don't have any control over the image quality. Setup for space structures is not possible.
2) There are no random event missions. This was probably the coolest feature of the original EAW's GCs and somehow it vanished in the FOC expansion. Nobody addresses this, it's one of those things that never gets mentioned because its a part of the base game and most modders work out of FOC. I think somebody finally addressed this and I believe it was the AotR mod team that was able to implement this system back into the game. This would be a nice addition to the mod.
People had actually figured out how to do this as soon as FoC was released. There have been a few things that stopped us from doing so in the past. For one thing, they would all require significant reworking to actually fit within the context and timeline of the mod. Some stuff was essentially close enough to our planet capture rewards that without some significant changes to them, we didn't see the point. Our story and scripting focus was on trying to improve and work out the kinks in the progressive GCs and more narrative stuff like the Katana mission. There will be a lot more focus on that sort of thing with, for example, the Bacta War, Zero Command breaking off from the Empire and the Pestage/Isard swap in era one, and the anti-Zsinj alliance fracturing after Zsinj's death to take examples from just the things we've already announced. Where it's feasible, we'll try to work in the smaller more random missions, but they have to make sense, and it has to be ones where having more factions than existed when they were a thing doesn't present a problem. Also, factions beyond those coded as the Empire, Rebels and Underworld cannot use story scripting, they only get access to what the game will load for the player with the AI's scripts, which means a lot of things like spawning in units through XML, locking units, and that sort of thing can't be done for them. Basically, it's something we're doing but won't always take the form you'd expect.
3) There are no "Victory Objectives" for the Galactic Conquests other than "conquer the Galaxy". That was another cool feature in the base EAW that disappeared in FOC. A lot of the objective's made sense, "don't let your leader get killed" or "conquer this planet" or "don't lose this planet" or even "do this within a certain period of time or lose". The main problem I have with the layouts of the Galactic Conquests is they are only supposed to cover a specific section of the Galactic Civil War, if that is the case the goal is to accomplish a certain objective NOT conquer the galaxy/map.
For example the Thrawn Campaign, a good example of the "conquer the galaxy" motif when that really isn't the goal. For the NR it's all about stopping Thrawn, that doesn't involve conquering the IR to do so. A Victory Objective for this GC would be to kill Thrawn and a few other Imperial Heroes and not lose Coruscant and the planets of the Deep Core. For the Imperials it would be the same; don't lose Thrawn and respective heroes, conquer the Deep Core, and maybe prevent the NR from getting the Katana Fleet. Since both factions are apart of the main three factions story scripting is possible here.
Victory Objectives would work for most, if not all GC's. Honestly the only GC's that have "conquering the galaxy" as the main objective would be the multi-era GC's.
Part of the reason this disappeared with FoC and FoC mods is they only make sense with two factions, and you're not really given a lot of options. Story scripting does open some new options, but part of the difficulty with heroes and planets as victory conditions is that the AI has no clue that's what they are, and while that can make the players forces more directed it's overwhelmingly likely the AI will send them in to do something stupid and you win within the first few weeks, especially on multi-faction maps. It is something I'm trying to play with for certain conditions, for example making the Krytos cure and taking Thyferra the way to actually win as the New Republic and something something Coruscant for the IR, with Zsinj in that map just wanting to control everything as per usual. We'll discuss the options for different victory conditions internally, including some of what you've suggested for Thrawn, however we also don't want to get into a position where you can win really quickly, easily or randomly because the AI has no idea what it's doing and really, no matter how good they are, autoresolve means if they use win-condition heroes or are attacked where those heroes are, they can't really escape that (and Black Fleet Crisis, Isard's Revenge and the Thrawn Campaign are the only GCs with 2 factions, so it'll almost always be a factor). For that reason I really doubt we'll really ever go that route. At least with planet combination win conditions the player has to take them from
someone.
This is where story scripting can come in, if the IR hasn't lost Myrkr by a certain day then they get a chance at getting the fleet(currently I haven't seen a method for the IR to get the Dreadnoughts at all, only the NR seems to have the ability in the 2.1 version of ICW).
The Remnant can get the Katana fleet in 2.1. I can't remember the full path of the mission for them, but start by conquering Pantolomin.
4) There are no planetary bonuses or the current bonuses are extremely unclear. We (Veteran ICW players) all know Wayland has cloning facilitates but it doesn't say so in the planet description, just something about Light Frigate Shipyards being present there and to see the Era tree for build-able options. It would be nice if those were reintroduced into the game giving the planets some kind of strategic value other than being Capital Shipyards and having the ability to have up to five defense platforms. That also should be in the planet's description, how many defense platforms can be built in orbit and what kind are build-able. It would really help when planning an invasion.
This point probably turned into more of a point to make the planet descriptions more tactical than anything. Be that as it may planetary bonuses need to be reintroduced and made much clearer to the player. If planet's description said this and the defensive capability of the planet I think it would work wonders. Let's use Mon Calamari for example, "This planet has the capability of Capital Shipyards. It could house up to five defense platforms in orbit. The New Republic can build a ground structure to reduce the costs of the Mon Calamari line of Warships at this planet." Same for Kuat, the only thing difference would be "The Imperial Remnant can build a ground structure to reduce the costs of the ISD-line of Warships". Something like that but a little more refined.
As far as documentation goes, that is something we are working on improving.