Before launching an attack, a good player already knows how it will end. Simulating combat avoids losing your fleet in a miscalculated attack, and when several of you attack in ACS (combined attack), splitting the loot fairly avoids arguments.
Simulate before attacking
With the target's espionage report you can simulate the battle: how many rounds it lasts, who wins, your losses and theirs, the debris left behind and the chance a moon forms. Since combat is random, look at the average of several simulations, not a single one.
Rapid fire and debris
Rapid fire lets some ships fire several times per round: that is why a handful of Cruisers shred swarms of Light Fighters. Debris (metal and crystal from what is destroyed) floats for recycling; in many universes part of the defense also goes to debris.
The ACS split
In a combined attack, several players contribute fleet and share the loot and debris. The fair way is to split by what each contributed or by their losses, refunding first the deuterium spent on the trip. Doing it by hand is tedious and error-prone.
Tools for this
Use the Battle Simulator to anticipate the outcome, and the ACS Splitter to divide the loot among attackers with the different split modes and get a result ready to paste in the forum.