At each location, there are things that can be done to benefit one's side.
Glaive Throwers in Isle of Conquest are largely anti-personnel weapons. They only have a driver's seat. They have two attacks available: a direct (single target) attack that does a fair amount of damage, and a channeled area effect burst.
While their direct attack can be used against individual targets (at range) or against keep gates, it is their area effect attack that provides their signature benefit. Their range combined with their area effect attack make them highly suited to clearing the keep towers of defenders, or for causing havoc among clusters of combatants. Like most siege engines, they are much less maneuverable than individual players, and are susceptible to close-in assaults.
Soon after capturing the Workshop, four demolishers spawn. These siege engines operate much like the Wintergrasp Demolisher, in that they have a fireball (fiery boulder) ranged attack, and a 'melee' ram attack. Additionally, they have room for two passengers, who are protected by the Demolisher and may attack, but have no vehicle-granted abilities.
Both of the Demolisher's attacks do siege damage, with the ram doing about 30% more than the boulder. The hurled boulder, though, has the advantages of range, and does damage in a 10 yard radius. It is highly suited to most offensive roles, but is most often seen doing siege damage to the enemy keep's gates.
After holding the workshop for 3 minutes, the Siege Engine will be repaired. (If destroyed, a new one will spawn in 3 more minutes.) The Isle of Conquest Siege Engine has the most active positions of any current World of Warcraft siege vehicle:
The siege engine can do massive siege damage if it can get into range of the target. However, it can also be overwhelmed if swarmed by defenders, particularly those able to deal damage at range. It may excel at defense, though, with numerous AoE attacks and no pesky tower guns striking it.
[Seaforium Bombs] are used exclusively to cause damage to the opposing keep's gates. A player may carry only one at a time. As in Strand of the Ancients, these devices must be placed (a short channeled effect), then defended until they detonate (10 seconds later). Enemies may disarm bombs that have been placed, again, by a channeled effect.
Once placed, the bomb disappears from inventory and a new one must be acquired. The bomb is also dropped upon death.
Three achievements involve bombs in this battleground. The Seaforium Bombs and the [Huge Seaforium Bombs] (see below) are considered separately for the respective achievements.
There are several Airship cannons mounted on the airship. These cannons do AoE damage both to players and gates. While the strength of the guns is not great, it does damage comparable to the hurled boulder of the demolishers without the vulnerability of that siege engine. While the airship is not always within range of the enemy keep, there are usually enough targets available to keep the operator busy.
All people on the airship are granted the parachute ability. The parachute deploys once you leap off the airship, and lasts until you land ... on something. With only modest amounts of practice, one can parachute into the opposing keep's courtyard without waiting for the gates to fall.
You are also able to cast and attack players as you are falling down.
Each of the keeps has three gates. The defenders have portals at each gate allowing travel to the other side. The attackers must do siege damage to destroy these gates in order to gain admission to the keep. (Other means exist: The airship, and the catapults.)
Each keep has two towers, one on either forward corner of the keep. Each tower has three easily accessible guns.
Each tower gun has two powers: Rocket Blast, which deals a hefty whack to everything within 8 yards of the target location. And Incendiary Rocket, which has a smaller area, but deals damage over a period of 15 seconds with a 30 second cooldown.
Keep tower guns are useful against both attacking siege engines and attacking players. They are, though, subject to attack themselves. When destroyed, players can repair them through a fairly short channeled effort. Note that enterprising players may land on the keep towers and attack the guns directly, much to the distress of the gunners.
Much like the Seaforium Bombs from the Workshop, ... but larger, and closer to the gates. Like those other bombs, they can be planted, and will do siege damage to the gate unless they are disarmed. You use them against your enemy's gates from the inside, or disarm the ones the enemy tries using against you.