First Grow

I am starting a grow. Right now I have 2 bag seeds of some of the better mid in my area(just to try it out). I also have germinated 5 Ice seeds and % Hash Plant seeds. In the first picture is Plant A. In the last is Plant B. In the second picture both plants are beside eachother, which leads me to my question, why do they look different? They came from the same bag. Possibly an F2 generation with different phenotypes. Or possibly one just stretched a little more than the other? In the third picture does it look like I have enough nodes to clone for sex? If not, how many more would I need. And finally, in the lfourth picture, what is the cause for the brown spots? over nuting? too much heat? bugs(which I doubt because I am thorough with my sanitation)?

Thank you to anyone who can help!