I don't know if you guys just missed or overlooked it or thought it wasn't important, but this is by far the biggest, and best change the character has seen yet:
This means µ will have corner 5-way mixup based on a completely invisible offscreen stein's firing timing.
She's crouching, though I know her standing animation is pretty deceptive.
Habaya has multiple hit instances, so I'm confident it will overpower the successive greater projectile power of Phalanx Cannon.
EDIT: Confirmed - http://www.twitch.tv/adastream/b/345973036?t=98m55s
Grounded Habaya is better for keepaway and for using as a meaty, so it looks like we'll have to prioritize that one more, though the µ player in the video wasn't using habayaa at an optimal tk height for it to be plus or safe at all.
As for guard crush, remember that if she has 50 meter she can just put out a meaty Totsuka and do 2 CT's in a row!
It's less which D you use and more being aware of when your steins will hit. Because all steins have the same tracking and equivalent firing speeds [excepting 5d], using steins in neutral or for pressure all comes down to experience and knowing what your options are when they're on the screen.
Oki Setups are a great way to learn how to use steins though, as most of the timings are intuitive and already built into the character's combos.