Listen to your body.
-Will drinking filtered coffee/hot lemon water/green tea HALT THE KETOSIS?
stay on clean water for the sake of your health, taking anything else may cost you some very unpleasant symptoms, learn from experienced water fasters.
-How exactly am I supposed to know when to end it?
It is too early to worry about that. You will find out when the times come.
-is it ok to drink an electrolyte mixture (the ones that they sell for babies in powder form) once a week to replenish some potassium?
Listen to your body. People who drink too much water may loose too much minerals.
-Would it be dangerous if I walk for 2 hours everyday?
(That's what I've been doing for the past 4 days-and before that of course).
Listen to your body. If you feel weak, it is a sign of low blood sugar, meaning you have pushed your limits.
-How MUCH water should I drink?
Per thirst. Listen to your body.
WS