that hand attack will be nerfed in the next patch, a few less fireballs will spawn and it'll overall just last less time after the final slap, I do find it to be a bit bullshit too.
for that orange attack, yeah no just move in diagonal patterns it's the best way to guarantee you don't accidentally press two opposite keys and stop in place (you do get a couple of frames where you're still considered moving if you stay in place however)
lastly it's not that those defense buffs don't stack (they do) it's just that I can't code for shit apparently and defense just doesn't do anything at all unless you edit your save file to have like 90000000 defense (this will also be fixed in the next patch)