Syntax: Skill + 2d6 - Difficulty (Easy: 14, Medium: 18, Hard: 23, Extreme: 29, Insane: 36)
If you are trained in the skill you apply excess succes, fx: Medic using medkit: Medic(9) + 2d6(8) - Easy(14) = 3(Succes) -> Heal Wounds 1d6+4(8) + 3 = 11 wounds removed

Weapon Ranges:
Short: 0-5" (Within CtrlZone) So far used to give Shotguns +2 Aim
Medium: 5-10"
Long: 10-24", Aim -1
Extreme: 24-48", Aim -3
Ridiculous: 48" and beyond, Aim -4
The effective range of the weapon may not reach that far, but I'll let you try with Aim and damage -2
There is of course the option of mounting a scope, to improve the aim on long range

Weapon Requirements:
Using a weapon, involving a Strength requirement, will lower your attack stat by: Req - your Strength