For the first one, yeah, there are lots of different air chains you can do, but it depends on height, which is related to the second one.
In theory, assuming you know which side you'll be on, and get a very low hit, you can actually do:
2B(4), j.C, j.2C, jc, j.B, j.C, j.D, j.214B [2246]
I'll edit it though to show the various options.
For the second, you can remove one of the two normals after the first jump cancel to ensure the j.214AB wont whiff. You have to get them quite low to do both.
For the last one, I personally don't use this combo, its very difficult. I have seen Tahichi use it and Lord Knight demonstrated it on one of his streams. Try doing it in the corner if you want to see it work, its a lot easier there. And yes I apparently cut off the ender somehow.
Edit: okay, fixed it.
2B(4), j.2C, jc, j.B, j.C, j.D, j.236CD, 2D, j.22C, 214C, 2B(4), j.2C, jc, j.C, j.2C, j.214AB [4213, 50 Meter]
Much like with the combos that end in a j.214B with Margaret almost touching the ground, the same is done here, she has to be extremely low when you do the j.236CD such that she lands, recovers, and can 2D in time to grab them while falling. Very tough to do consistently in matches with the variable height of anti airs, since they need to stay as low as possible as well.
https://www.youtube.com/watch?v=51KAV8CO7UY&feature=player_detailpage#t=198 here is a video of Tahichi using the same route off a different starter, right at the timestamp. CH j.C, 5C, j.2C, jc, j.B, j.C, j.D, j.236CD, 2D, etc. Its a lot easier to get the height right off this.