GH Waterfarm Advice Needed

I'll try to make this short & sweet, I emphasize 'try' greatly. Started in soil, moved to soiless, now enticed by a GH (or homemade) waterfarm system. They seem easy enough to make at home, and cheap enough to buy online. I get the general idea of how it works but I have a few questions.

-What happens when your roots grow into the nutrient solution? Wouldn't root rot take place, or a clogged pump?
-How much solution to put into your waterfarm?
-When would I check my pH?
-How would I know when to change the resevoir?
-What's a good ppm to go by for the different phases of growth?
-What's a good nutrient lineup to go with for waterfarm, I'm done with FoxFarm, I'm enticed by General Hydro's FloraNova + Additives.
-What happens during a power outage?

Any & all answers to these questions would be greatly appreciated, just a fellow farmer trying to get his thumb a lil' greener

Also,

-Do I feed during "lights off"?
-Whats a good ratio to pump on pump off? I've heard 1 minute on, 5 minutes off.

The water farm uses a air pump outside the unit dissolves o2 in the water when it top feeds you might want it on a timer so you are not. Constantly top dripping in my opinion I also added an air stone to the bottom of my unit by drilling a small hole right above my fill line

Oh I have used botanicare bro blend adding cal mag if you are using RO water and adding advanced nutrients product called sensizym it's just microbials and bacteria that feed on dead root material. I ph at 5.5-5.8 . The unit takes about two gallons my momma uses roughly a gallon a day so topping it off at 5.5 will straighten up your ph my unit never sems dirty or anything I have only dumped and cleaned it once in two mounts I just keep topping it off I feed five times a day 15 on whatever I between off