I'm not sure about the 5:1 question... but as for skill trees, it's a matter of preference. You have two choices:
Hueksal, Ice, & Lightning 110: Magic Damage Increase, Parry Increase, Phantom Walk (great for job wars)
Hueksal, Ice, & Fire 110: Magic Defense Increase, Status Immunity (with proper blues on accessory), Stealth & Invisible Detect, Physical Damage Increase (good for hybrids), Firewall (Protects you from Warlock stuns & status effects, also helps against wizards)
Personally, I go with Ice Fire Spear... works out good for me