I didnt use ACV very much when i first started washing with baking soda. Since my hair is locked up more now, i use it when i wash. I think it helps because i wash once a week lately and my scalp starts to itch as you mentioned. After a ACV rinse it doesnt itch.
ACV is really cheap if that is your concern... like $2.00 for a big jug of it.
But to answer your question no i don't think that it is necessary every time.
I have some sections that are determined to congo because the hair is still very young in its dread journey and my parting was shite. I threw in a couple beads around there and they help a little bit but are still always congoing even around the beads!
:/
I did my dreads on my own and i was determined to do something in order to "make my dreads" I was hardcore pro backcomb and pro TNR.
I sectioned my hair with a rat tail comb and rubber bands as best as i could with a hand held mirror and a bathroom mirror. the only space where i wasnt able to make good clean sections was that part where the back of the head meets the top of the head... its hard to see from above and from behind. Regardless i sectioned them as best as i could and began TNR all over my head.
It took me around 12 hours to do all of this on my own. they all came undone... Still determined to implement some method to start my dreads i backcombed at about 3 months keeping the sections that i had already made myself. some of them stayed in fairly well the majority came out again. From then i decided to quit killing myself with this dread process and just let it happen. My sections have held up pretty well over time and i think have served there purpose. Overall the time and effort i put into these starter methods was unreal and unnecessary. Looking back 5 months in from the backcomb (10 from the TNR) I wish i would have just went natural all the way utilizing separating as a means of creating the dread size instead of sectioning.
Regardless, without a doubt, sectioning or not, all my dreads love to congo with each other and you will be spending alot of itme seperating so if you think a perfect sectioning job will keep this from happening, you can go ahead and relax and just brace yourself because your going to have to do that regardless....
I suggest finding yourself a dreaded role model!! someone whos hair is similar to yours and that you would aspire to look like! this may help you when you grow weary of the messiness. trust me im quite sick of mine right now, but I know if I put up with it, it will be well worth the wait..
And if it makes you feel any better, your hair doesn't look anything like a rats nest... id bet it will get worse before it gets better.. 
its like golf..
I wish i knew... will be checking in to see what happens though. From what i can tell it looks like it turned it a lighter color. I guess i cant really see the problem to begin with. Have been interested in coloring a couple of mine too. good luck.
how many locs do you have?
I like yours man. The ones in the back are pretty gnarly. They look good on you. I say keep them. But only you can decide.
