You start with the following equipment in addition to the following granted by your background (a) a light crossbow with 20 bolts or (b) any simple weapon (a) a componants pounch or (b) an arcane focus (a) a scholars pack or dungeoneers pack leather armour, any simple weapon, and two daggers
Charisma is your spell casting ablity for your Warlock spells, so you use your charisma whenever a spell refers to to your spell casting ability. in addition you use your charisma modifier when setting your saving throws DC for a Warlock spell you cast and when making an attack roll with one