Technically, yes, it can make a difference, to some people. Everyone's hair is different, though. If a less expensive shampoo works in your hair, that's great. Some people, they need the more expensive products.
I have very long, very thick, very coarse hair. The cheap-o bottles of Suave and the like are simply not compatible with my hair. They leave it incredibly tangled and feeling generally weak. But my sister can use it all no problem.
Some people, their hair does not like silicones. I tried to go silicone free. My hair hated it. I need silicones in at least my conditioner.
As for conditioner, some people wash their hair with only conditioner because shampoo is too damaging for their hair. Occasionally, they'll wash with a clarifying shampoo to get rid of any build-up, but for the most part, they wash only with conditioner. If I do that, my hair gets too much moisture and it gets very stretchy. But others, it's the perfect amount of moisture for them. If you choose to wash with conditioner only, you're better off having two conditioners. One very thin conditioner to wash your hair, then a thicker one to condition your length if you feel you need it.
If your hair does get too much moisture (it feels limp, mushy, very stretchy), it means you need some protein in your hair to counter-balance it. On the other hand, if you get too much protein (it feels dry, brittle, crunchy), you need to increase the moisture you give your hair.
All that said, you just need to try out products and stick with them for a bit to see how they work with your hair. If you don't see any difference at first, just be patient and keep using it. Your hair takes a while to get used to new things. If your hair responds very negatively to it very soon after using it, I'd stop using that product, then. I've been told to stick it through, as well, because your hair still needs to adjust and figure out how to react to it, but frankly, if my hair is not doing well with a new product, I don't want to continue torturing it with said product. I've been growing my hair for far too long to do anything like that.
So. How do you know what you need when? It varies from person to person. As for me, I keep this on hand at all times:
1. Dandruff Shampoo. I get horrible dandruff if I don't use it.
2. Moisturising Shampoo. To give me moisture when I need it.
3. Protein Shampoo. To give me protein when I need it.
4. Thin Conditioner. To conditioner-only wash, or to mix with another conditioner, or for use on my scalp, if needed. (Yes, I said that conditioner-only doesn't work for me, but I can do it occasionally if my hair needs the moisture. I just can't do it all the time.)
5. Thick conditioner. Used in combination with other conditioners, or on the hair from the nape of my neck to my breasts.
6. Thicker conditioner. Used in combination with other conditioners, or on the length of hair from my breasts to my hips.
7. Thickest conditioner. Used in combination with other conditioners, or on the length of hair from my hips down to the ends.
The longer your hair is, the older it is, the more moisture it usually needs. Occasionally, I may swipe a pea to a dime-sized amount of coconut oil through the length of my hair when it's wet. That's about as much as my hair can handle without getting oily. I know some that can slick a good tablespoon or so through their hair and it just soaks it all up. The trick is to start with the least amount possible and move up from there. I chose to ignore that advice the first time I oiled my hair. I figured, "My hair is so long, I'll need that tablespoon of oil." I should have listened to directions. >.<
The only other products I keep on hand are a moisturising detangling spray, a "smoothing cream" which is basically various oils in some other products that I got as a free sample (coconut oil alone gives me the same result, so I won't likely purchase that stuff after it's gone), some gel thinned with water in a spray bottle, and a bottle of mousse. The gel and mousse are products I use for only a certain hairstyle.
As for your flake issue, maybe trying a light dandruff shampoo could help. Or if you want to stick with something more natural, maybe a tea tree oil shampoo, or even just some tea tree oil itself. I've heard that that helps against dandruff. Just play around with stuff and see what works for you.