Gnats, Nuts and Dying Leaves

Okay I am 10 days into flowering. So far 2 dayz into flowering Gnats appeared, but they were only 3 or 4 and have since then been murdered. I am going to top the pots with 1/2 of sand incase it turns Out to be fungus gnats. I have been gnat free for 3 days.
Does having a few gnats always lead to getting fungus gnats?
Also one 2 of my plants near the bottom the first set of tru leaves that are 4x the size of all other leaves are yellowing and browning. This happend in another plant when the leaves got abouth 7-8 in tall about 3 weeks ago.
Is this normal for the leaves to do that?
Also I got two plants with 5 main colas and no other growth and three bushy as can be one with 1 main and 6-7 other lil minis growing? Is this genetics?
The floweirng food I bought was made to be cut into soil they are small green circles with a NPK of 15/30/15. I just threw some into water for a couple of dayz and watered my plants So far they are going good into 3 waterings 10 days into it.
Finally outta 6 I have flowererd all had pistils but one grew balls too and had to go. four days later I discoved what I thought was one ball growing outta the toppest main node and took out the ball. How long into flowering can balls appear am I gonna have to be viligant all flowering period? I check every inch every day.

Where do the buds form? Is it at the top of the preflowers and go down the stem?
I was just curious as to that goings on above other then that this grows been eazy and fun I think my gurls look awesome they are about 2.5 ft.
 
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