Still can't beat 16F.
What is the reccomended about of skillpoint distribution amounts for my point in the game (how much into main stat, how much into backup stat, how much into weak stat, etc.)? I feel as though I'm behind.
There's no set rule for this. But I go by how much it costs to purchase each skill level, and use that as a measurement rather than the actual skill level. Then I make it so all the sky-high or important stats cost double the skillpoints to upgrade as pretty much everything else. Examples of important IMO are stuff like patchy's mnd and mag, tanks def/mnd/hp, Aya/chen's speed, Remi/yuugi/chen/flan's attack, etc. Treat squishy caster mnd like you would treat a tank's defense. It really makes them survive everything anybody else could but unlucky single-target melee attacks.
If you want to be even more efficient, instead of pumping the important stats even more, I suggest figuring out the less useful, but actually used stats out, and making them cost 1/3 or 1/4 as much as the important stats instead of 1/2 like everything else. For example, I find stats that fit in this catagory to be stuff like patchy's def, Reimu's atk (yes her spells are composite, her support spells are not though, and I don't use her as a nuker), Kaggy's mag (important for those high def trash, but once she can one shot them, it fits here, because during bosses, she's basically only good for the stone bowl spell IMO), Tenshi's attack (hong's attack is actually fairly useful IMO since it affects her heal amount by a decent amount), etc.
I haven't a clue how one should spend points on resists though. I tend to ignore it, then blow millions of skillpoints into them semi-evenly once in awhile. They always tend to cost alot less than everything else though. Alot of the time when I blow my points into them, I think I can really crank up their level because they are so cheap. But if you do every element, you'll be suprised at how little they go up before you're out of skillpoints!
I never really gave nature preferential treatment here, but now that I think of it as trance mentioned earlier on, I DO seem to notice overgrowth and earthquake tend to make me cringe more than most spells.
