To plumb washer system to cooling system simply, use the lower pipe that runs at the back of the rad, the one that normally corrodes and leaks, join the end of this to some copper pipe running through the washer bottle, and out again where you join it to the end that would have gone onto the metal pipe that corrodes.
NB I changed my metal pipe for a piece of Marine Grade stainless pipe, cost £4, but cheaper than a seized engine!!
The advantages of 85/90C water in the washer bottle is it removes dead flies perfectly in the summer months, and stops it freezing in the winter months.
I cannot detect any difference in the car heating up heater wise does not seem to take any longer that you can notice.
tabetha