About the 2b, 3c, 22d IAD, 2c 214c, land 2c, 8d ...
I'm still learning to do this, but I think I can offer some advice on the 22d...
At first, I tried doing it straight after 3c, but half the time Nirvana would end up on the wrong side. I noticed in Japanese videos the summon would actually happen at the beginning of 2b, so what I figured they were doing was using the 2 in 2b as the second 2 in 22d.
So when I do 2a, 2b, 3c ... I do 2a (return to neutral) 2b+d, 3c+d (hold d on the second one) etc. Done correctly, this will get Nirvana in the correct position every time. If it's not from 2a, then I suppose you could do 22b+d for the same effect.
I can't quite do it consistently yet as it is pretty tough, but I think this is probably the most economical way to get it consistently that I can figure.
EDIT: Actually I'd like to correct myself! This may be summoning too early! I'm not positive either way, as I'm still trying to get it down 100% (getting closer!). What you may want to do is 2a, 2b, (return to neutral) 2d, 2c+d (hold d) etc. If someone who can actually pull this off well wants to say which of these is better (if they are at all!) I'd greatly appreciate it!