in regards to the first question, I use the back of the hand method and things seem to work out. If it's too hot on the back of my hand, it's too hot for the plant. Of course there is a much more reliable and scientific response to this...with temps & rh we have to worry about how well the plant transpires and what the uptake is/can/isn't. There is no problem moving the smaller plants closer to the light as long as the plant isn't getting too hot & isn't getting a breeze. LST is super easy and you'll be happy if you try it out.