Weapon Set Questions

Can somebody please explain or point me to a thread about caster weapon sets. What are the options and how do I achieve them. I know people use spears/shields and wands, off hands, and a staff but what does all the 20/20 and 40/40 mean. How do you get them

20/20 = 20% Half cast time and 20% half skill recharge
40/40 = one 20/20 wand and a 20/20 focus
shield = +30 hp and +10 vs x damage type
-5 en spear/sword/axe with +30 hp and a +5 en spear/sword/axe with +30 hp

You also use "High energy set" which contains:
Offhand with 15/-1 and Wand with 15/-1
You can also "Hide energy" which you use to hide your energy so mesmers can't get it. Then get a sword/axe/spear with 15/-5energy set.