I'll just answer a few of the questions. My 'goal' is classic/ midthigh, but that's just a placeholder goal in my mind, even though I had it before I joined LHC. I have had long hair(around my goal length) for years and years, but cut short, for me, to shoulder maybe 2018/19. Not sad I did it, but I quickly decided I liked long hair better, so I'm just growing out right now. My approximate plan is to maintain at my goal for a couple small trims, make sure I'm happy with the hemline, then keep growing until I decide it's too long, and cut back to wherever I remember being happiest with it.
I don't really care about the thickness, but I don't want really thin ends, and since trimming is a bother that I don't get around to often I will try and pick points to maintain at for short whiles to convince myself to keep the split ends in check and not feel like I'm losing lots of length. Currently I get my mom to trim my hair every year/ year and a half or so, out of laziness mostly. Last trim I asked for an inch off, and she took about 1.5, but I trust her to know how much needs cut and to make it look decent, and it's just a small amount of hair in the end, so I don't worry if she cuts off a bit more than I wanted because it will be so long since I get it cut again, and it probably needed it.