For your first three "ifs":
if you try to go above your "take 10" value, then you're taking a risk, and if you succeed, then your seed is more powerful than what it normally would be. If you fail, you fail and the attempt to be more powerful was wasted. You can still take 10 in most situations, including combat (this is NOT A SKILL, it follows different rules, and the only thing that prevents you from taking 10 is being threatened). The only reason to risk failing is if you, for some reason, need extra power. Otherwise there are uses for rolling wihtout a risk to fail. The exceed augments don't increase the DC of the seed. So, for instance, Boulder Toss. You start with a DC of 30, and can either take that as is, or increase it by 6 points to affect an additional target. If you do increase the DC, it is now DC 36, and you'd need a check of +26 to take 10 and succeed. If I instead had a check of +35, I could roll, and not risk failure, but have a chance at getting an even higher bonus to the bull rush, so if I rolled a 5 I'd get +1, if I took 10 I'd get a +2, and if I rolled a 17 I'd get +4.
I am expecting most people to just take 10 pretty much all the time, but the rolling allows for some chance in the power. You will almost never even have a chance at failing a bending check, because you can always choose to just not increase the DC, and with most seeds, it'll still be relevant thanks to the exceed augments.
1: I forgot to add the augment that makes the concentration a swift/free action, and the DR is supposed to be the real power. I may up the AC bonus, but it shouldn't be much of a problem (it's 1/2 Inertial Armor progression, but you add DR and energy resistance to it). The main power from this one comes from the exceed (well, it should be exceed) augment that grants DR.
2: I'll add it, it should have been there already.
3: It's not an area blinding. It's a targetted effect that deals damage and has a chance to blind on a failed save, and on a successful save they still take a penalty. And again, you can increase the DC, damage, or duratino of the blinding using augments. The save is an exceed augment, so you can forgo most of the damage to force them to make a high DC save against the blinding. Not only that, but I'm not basing my balance on tier 1 classes or casting in general. Screw casting.
4: It's also an airbending seed. The difference: air uses wind to whip up dust, and earth moves the individual particles to whip up the dust.
5: I'll add more words, but it's referencing the Bender class chart.
6: Why? It's not an SoD. It's not changing to one.
7: I took that out. I didn't want it in there, and there's a different way of doing that. This isn't intended to be a SoD, it's more of a capture thing rather than the spell Imprison. The PrC Agent of the Dai Li has a more advanced version, where they take you into the ground, rather than this one, where you shoot arms of earth up to grab someone. This does not pull you into the ground like the spell does.
8: First off, it lasts only a few rounds. Also, it ends when you lose sight of the target. Finally, it can't force the target to take any mental action. So it's more limiting in many ways, but less limiting in some others. With that in mind, is it still too powerful? Oh, and you can't affect just anyone, it has to be a creature with the Earth subtype.
9: The "unconcerned" thing is supposed to be "you can move through using only 2 squares of movement, but you automatically take damage". There's some extra words that shouldn't be in that seed though.
10: Okay...what's the problem? One is a line, the other is a cone. One moves creatures better, the other deals more damage. I'm going to switch the damage though, it should have been 1d6 for the rubble, and 1d4 for the wave.
11: There is.
12: is there any confusion? If not it's fine, but if there's confusion, then I will clarify where needed. So where's the confusion?