I have 2 questions that I should probably already know the answers to....
1. How much ablative armour do you need on a missile before it has an effect? i.e. does it need to be integers (1,2,3 etc) or are fractional values useful?
Fractional values do help. The formula is: Chance to Hit vs Armour = (Weapon Damage / (Missile Armour + Weapon Damage)) * 100%
So if the armour was 0.5 and the weapon damage was 2, the formula would be: Chance to hit = (2/2.5)*100 = 80%
2. Same as above but replace armour with ECM.
Yes, fractional is also useful with ECM. ECM strength per MSP depends on your ECM tech but lets assume you have ECM-2 so 1 MSP will add 20 ECM strength. If the missile has 0.5 MSP dedicated to ECM, it would have an ECM strength of 10. That ECM strength is deducted from the percentage chance to hit vs the missile after the basic chance to hit and crew grade is calculated but before tracking speed is taken into account. Each point of ECCM will counteract 10 strength points of missile ECM.
Steve