There's no such thing as faster cast or recharge upgrades that you can add to a Staff. Your best bet is to get the Desert Collectors Fire Staff that already has those mods.
Staff upgrades you can put on a staff are as follows:
3 Heads
Defensive Head: Armor +1-5
Hale Head: Health +10-30
Insightful Head: Energy +1-5
6 Wrappings
Fortitude: Health +10-30
Defense: Armor +1-5
Warding: Armor +1-7 vs Elemental Attacks
Shelter: Armor +1-7 vs Physical Attacks
Enchanting: Enchantments last 10%-20% longer
Attribute: Specific to types of magic you possess. Such as Blood Magic +1 (10-20% chance while using skills.)
And each staff can only have 1 head and 1 wrap.
WTB Fire Staff Upgrades
Arcanis Imperium
HellFireRaiser
actually the max firestaff with the perfect casting mods is outside the ice caves zone in talus chute for 5 firgid hearts
Arcanis Imperium
thanks, I had no idea if it was in the desert with the rest or not.
Ventashar
20/20 staff w/ +30 hp and +5 energy, chances are you won't find me in game so msg me on here or AIM L0stBeforTheDawn