Yup watering first thing in the morning is best... They will droop for a bit how long will depend on root temp and drainage. Wait 2 days and saturate the pot first thing. By midday they should be well perked up usually no more than a couple hours
Yup they do because they stop transpiration and only continue respiration for the most part during the Calvin cycle.
You know how your plants start to droop before lights out? Yes there is a kinda clock effect but this also happens more pronounced under very high light. It's as you start getting closer to the light saturation point. CO2 concentration affects this significantly. As plants get closer to light saturation they start photorespiration won't go all into that but they will basically start to droop a bit because they are closer to absorbing the maximum amount of photons at that rate for the day in a sense. CO2 will allow them to be under higher light for longer because it affects this process and that's how CO2 increases growth rates. Without adequate high light you won't really see any benefit from increased CO2.
Feed from the top... Bottom feeding makes for all sorts of new concerns and issues. Water until the media is saturated completely. Everything should be wet. You may find using something like a straight coat hanger and pressing into the soil help if you have dry spots that just won't take water. Scratch up the soil surface to prevent channeling. Once you get it all saturated you should be good from there on out if you continue to water properly.