First of all, land combat in this game is based largely off of air combat, being that space combat is the primary form of combat, and to invade a planet you must pass through the atmosphere. This makes air units a very important part of Star Wars combat. As such each side boasts its own unique and powerful air units, while on the ground, units have been mixed to better allow a combined-arms approach to land combat.
The Empire without a doubt has the single most powerful ground unit in the game; the Acclamator Assault ship. This powerful ship is capable of laying waste to improperly defended worlds with ease, and when at altitude is immune to all but massed airborne defenders. In addition, it is not defenseless if caught in space, boasting capable defenses similar to those of the Acclamator 2. However, this powerful ship is not without its drawbacks. For example, due to the Empire's dependence on self contained systems, the Acclamator is the only air unit available to the Empire. And while it contains either a compliment of powerful MAAT Gunships or TIE Fighter scouts, it is not available until Tech 4. This means that as the Empire, you must be prepared to endure unopposed air attack early in the game, so stock up on air defense units as well as base shields. Later in the game, however, you will be able to overwhelm all but the most heavily-defended worlds with ease. Use the TIE Fighter variant to scout targets for your big guns, as the TIEs just aren't very effective at ground attack and are very vulnerable. The MAAT Gunships, on the other hand have many uses, especially against shielded worlds. Use them to locate and destroy the shield or power generators to allow the Acclamator to destroy the base. Outside of air units, the Empire generally possesses the most powerful ground vehicles and infantry. Their vehicles are generally better armored and have better firepower than their Rebel and ZC counterparts, although they are vulnerable to air attack. Imperial Stormtroopers are also better protected and come in greater numbers than their counterparts. However, as far as infantry goes, this means little, as suprise and defensive positioning can mean the difference between victory and defeat.
The Rebels and ZC rely on similar tactics to defend against and defeat the sheer power of the Empire. Both gain air support much earlier in the game than the Empire, which is a good thing considering they are both heavily outmatched in a straight-out ground confrontation. The Rebels possess as much variety in their air units as the Empire, but with a big difference: they can build theirs individually. The Snowspeeder is the same as you remember from vanilla FoC, just a little faster and perhaps more survivable. The LAAT Gunship is extremely similar to the Imperial MAAT, both acting as the attack helicopters of the battlefield. The LAAT boasts missiles and particle beam weapons, making it dangerous to vehicles and lethal to infantry. It is decently survivable against ground-to-air weapons, but very vulnerable to enemy aircraft. Finally, the Rebels possess the X-Wing, the single most powerful air unit in the game (besides the Acclamator). This craft is deadly against both air and ground targets and is equipped with both proton torpedoes and heavy laser cannons. Two or three squadrons of these is enough to defeat an Acclamator if properly utilized, and are also cheaper.
The ZC can only build one air squadron, which is both a blessing and a curse. The one squadron the can build is a combined force of one V-Wing armed with missiles and heavy laser cannons for ground targets, and two Z-95s armed with laser cannons for air targets. This is, however, a case of Jack of All Trades, Master of None. While the ZC is capable of constructing a cheap air force which is effective at many roles, they lack the variety of the Empire or Rebellion, and their units are less effective at AA or AG than the others'. The simplicity and reliability of their units, though, makes it easier and cheaper for them to bring air support to a battle than the Rebels, and certainly more than the Empire.
As in space, neither the Rebellion or the ZC units are a match on-on-one for their Imperial counterparts, for the most part at least. Therefore, as a Rebel or Consortium player you must utilize a combined arms approach to defeat your foe. Air support is key, as it will allow you to counter higher quality ground units from the safety of the skies. A good tactic is to locate and destroy the enemy anti-air with your ground units and artillery, then pull back and allow your air units to finish off the enemy on the ground. This tactic doesn't only work against the Empire, and you can use it against both the ZC and Rebels as well. The Rebel player should work to build X-Wings and LAATs as quickly as possible, coupled with Gallofree Transports to make your forces completely air-mobile. Snowspeeders make good pathfinding units, and as always are effective against ATATs. Use your X-Wings to destroy enemy aircraft and exposed light vehicles quickly, while your LAATs destroy heavy tanks and infantry. The deploy your infantry sqads and use your Gallofrees to drop off tanks or artillery near the fighting. The Rebels ability to move quickly and avoid direct confrontations with superior enemy forces is not only effective in space, but is crucial on the ground as well.
The ZC possesses decent units all-around in ground and space combat. They combine low-tech but useful weapons and average soldiers coupled with a few hi-tech toys and well-trained troops (similar to Nod). On the ground, their infantry significantly less effective against the Rebel or Imperial troopers....unless they get close. Then their grenades can do massive damage to clustered infantry and even tanks. They are extremely effective against Jedi and Sith, which balances their usefulness in infantry encounters. The ZC player must balance his cheap expendable units with his more expensive ones to be effective in ground combat. Destroyer droids can be used to quickly move forward and secure drop zones, while Z-95s and V-Wings can provide overhead cover against heavy ground units and air units, although make sure to have a numerical advantage when facing X-Wings. The ZC also has the advantage of combining its heavy tanks and AA defense. Canderous Tanks can be used at the center of an attack force to provide cover against low-flying aircraft and to screen lighter units such as missile artillery or plasma tanks from attack while they use their heavy firepower to hit defenses (or attackers) from a distance. Remember to protect those high-credit units as much as possible, however.
On a special note for Rebel or ZC players facing heavy Imperial attack (by this I mean "Acclamators are blowing up your base") base shields can save your life. Not only will they deny orbital bombardment and bombing runs over a wide area, they will also block fire from all air units above their coverage. This means that you can effectively neautralize enemy air power by hiding under your shield umbrella. This is the best way to survive an Acclamator attack, although you must be sure to defend your shield and power generators from dedicated ground attack vehicles such as LAATs, MAATs, and Snowspeeders, which can fly below the shield umbrella. To eliminate an Enemy Acclamator, you must use a large number of X-Wings or Z-95s and V-Wings. While destroying one can be accomplished with two or three squadrons, four or five is advised. The best tactic you can use is to quickly swarm it as it is rising after dropping off its MAATs or TIEs. Its point defense weapons are formidable, so you must quickly overwhelm it with small, fast-moving targets. Turbolaser towers are also capable of hitting Acclamators.
Well, hopefully this addresses most of the features of this mod. Good luck, and if you have any questions or can think of any other suggestions for the mod or a tutorial, let me know.