If a Staff gives +magic damage, does that only work when using the staff in melee or does it also give buff when using spells?
Also, does an equipped weapon in the second weapon slot give defence buffs or does it need to be in the active slot?
I'm sure there's a thread about it.
Magic damage works only with spells. If there's a specified type (fire, cold etc.) it will only work with spells dealing the same type of damage. It's a bit more complicated, but you'll learn that in time.
Combat rating buffs your melee hits. Fire/Cold/Electrical/Holy/Unholy works with all weapons, combat rating with a specified weapon type (f.e. polearm) works only with that weapon.
Items in the vanity slots or the inactive weapon set don't give any bonuses. But there's a difference which weapon you hold in which hand if you're dual-wielding.
Seriously - join a guild or hook up with some veteran. There will be more to explain the deeper you'll be in the game