in need of help!!!

my plants are about two months into vegin and i noticed that on one my main stem looks like its shedding and has white bumps growing up it. over the last two weeks its been slowly moving up and in the process it seemed to have killed my first leaves grown, i have no idea whats wrong and i was wondering if anyone could help me. Also on my lower leaves the tips look like they're burnt turning brown a bit, what could be the case?

and i have recently noticed gnats. what can i do to take care of them for good?

#1 prob is just normal maturation
#2prob is it fungas gnats? ive had them,no harm,just clean and neem...oil

alright sounds good. but how do you tell if their fungus gnats? i mean are their different kinds?

here are a few pictures. what looks to be wrong

I hate to reccomend this because its dangerous. But if you really want to effectively kill and clean your grow area of funus gnats, The only real way I know is a Pyrethrin fogger. Talk to your local hydro store and ask for it. Neem can work but its made as a preventative solution. And the tastes in neem oil are hard to get off your finished product. A couple good brands of pyrethrin: "Purge III" and "Doktor Doom"