I have enough time to answer your first question and I'll question your other questions later if someone hasn't done so yet
You can do 4B > 2DD > j214D > 66 > 6DD > D spam
You can do 4B > 2DD > j214D > 66 > 5DD > 236C on Carl, Rachel, Bang, Platinum, Relius and Tager.
I have only tested the second part on Carl, Rachel, Bang and Platinum personally but KaizerBlack, who told me about the 5DD link said it also works on Relius and Tager.