As far as reserving provinces, some people reserve them after they open them, but that's probably because they no longer have to worry about the hard/very hard levels. I would advise against that for you. Do not open them at all. Provinces that are already opened stay the same color/difficulty, even after you open the advanced scouts in the next chapter. The only provinces that the tech affects are the ones you haven't started already. The unopened/unscouted ones immediately go down a notch on the difficulty scale, both for fighting and for catering. That's what you need ... for the colors to go down from red and orange to yellow, at least.
That will be true for all the provinces ahead ... the difficulty level is permanently fixed at the level at which you opened it. However, getting a bigger squad size will help you to fight those large enemy squads a bit more easily, since your squad size grows. But the negotiation/catering costs remain high, and there's really nothing you can do to lower it after the province is opened.
Yes, you do have a ways to go before you start to see easier provinces, but the good news is that within a couple of chapters, you should be at a very good level. There comes a point in this game where the scouts take so long to complete (55 hours, in my case in chapter 16, and some have it worse than I do), where you can keep scouting all the time and never go above blue level (very easy) on scouts. 95 percent of my available provinces are blue level. Best of luck to you!
(And don't feel bad ... Been there, done that. I was overscouted big time too, when I was around chapter 3 or 4. Inno really should warn players not to do that.)