Am from scotland.
Q-1 They prob became like that with over fert, when they are babies they need like a few drops too like every 2ltr.
Q-2 They will still have fert ''nuit in their system your trying to flush that from them.
Q-3 I Run hydro and run on a timer, my timer comes on just as my lights go out, and for 1 hour, as they get bigger and stronger just keep adding on 15 mins, if the leaf tipps start to drop back off for a few days.
A good thing for you to have or get is those big WATER AT WORK bottles, i have about 3 of them and all pre made up and sitting to go, they hold like 18ltr, you should be changing your water in your res every 10 days, if your not its just being lazy.
What your looking for now in your plants is ( ANY NEW GROWTH) at the top.