No, only the sprinkler(s) in the area of the heat source activate, typically one to five sprinklers.
No, accidental activation of a sprinkler is extremely rare.
No, a sprinkler system is on call 24-7. Sprinklers never sleep!
The deluge of water from fire hoses causes much more water damage than water from a sprinkler system.
Yes, the loss of property from a building without a sprinkler system far exceeds that of a fully protected building with a sprinkler system.
1%-2% is all the average sprinkler system would add to the cost of a renovation or new home. There is not one other system you could install in your home that will provide for the safety and peace of mind for you and your family.