1./2. Just keep the rapid rooter moist(not soaked) until roots hit water. Keep bubble on from the start it will keep the hydroton(if ur using it) moist underneath the rapid rooter and the root will make its way down. 3 times a day was too much, like i said just keep rapid rooter moist(not soaked)
3. You don't need the chiller IMO, since ur using hydroguard and changing water weekly and starting with low 60's temp. My temps are 75-78 and i didnt have a problem, i change water weekly and start with 64 degrees. If its a real hot day i might drop a frozen water bottle in but i'd say i average high 70's with no issue. Don't overthink it, it's resiliant, thats why its called "weed".
Like someone else said, get ph to 5.8.