Ok..first couple shots are scorching..basically if you can stand the heat on the back of your hand..that's a good distance for your plants..
The yellowing and dying leaves is something else..I am guessing it's a lack of potassium...
Since you are flowering it's possible a couple of your strains are eating up your flowering nute supply faster than you are adding it..
What medium is that? Is it pro-mix? or is it something else?
What is the PH of your run-off water?
And who makes your ferts and what are you giving em?
Here's a link to a great chart...
http://www.overgrow.com/growfaq/97