List of questions - DWC

Can someone answer these questions for me, specifically for a DWC setup.
1. What pH do i want my water pH level at with nutrients mixed in?
2. How often should i top up my water and nutrient mix?
3. Should i replace the water and nutrient mix every week, 2 weeks etc instead of topping up?
4. How often should I add either pH up, or pH down?
5. Where should i buy water from?
i.e should i use bottled water or should i splash out and buy R-O water from a hydro shop?
6. Can i use tap water that i have left in the sun?
6.1. How long should i leave water in the sun to remove chlorine?
7. What does the water ppm mean and how do i change its ppm?
7.1 What does the water ppm effect?

Please add any pointers you have that are important to know for a first time deep water culture grow. Thanks fam

Will update with more questions i have in the near future.

Quite the list, first i would reccommend reading any book by Ed Rosenthal, or Jorge Cervantes. Both absoulte gurus on growing. From what I've read, and thats about all i have to go on as I'm fairly new myself, but I'll try to help

1. Ph Ideally 5.6-5.8 If mine get above 6 i start freaking.
2. I check my water and ph levels twice a week. Digital ph meter is the way to go.
3. Everything I've read says replace weekly. In veg i replace every 10 days and in flower, weekly.
4.Answered in #2
5. Start with distilled water from anywhere. I've use rain water. (My wife HATES the buckets)
6. Heard of it working, never tried it. Advice: google.
7. PPM-parts per million, the concentration of disolved solids in a liquid.
7.1 if your ppm rating is too high, your little one can suffer from: nute burn, nutrient lockout, and death. Over feeding kills!

I hope these help.
-Joheim