I forget the video but it pointed out that st.A cr.B st.A xx fireball is a much better blockstring than anything into f.B xx fireball for similar reason. In theory f.B is pretty bad - punishable on block, really easy to see coming & guard roll, etc. Many players don't know this and don't punish accordingly, but it's good to know it's not a strong option. By canceling the jab into fireball you are much safer against guard rolls and such. Not to say you can't ever use f.B in pressure but just know that if every string ends in f.B fireball a good player is gonna adapt to that.
I'm finding cr.B into st.D a better frame trap than using cr.A simply because the range of better on cr.B.
first drive cancel into crescent kick but then when I do his rapid punches -> finisher then go for the DP+B it always whiffs
Are you letting the rapid punches come out at all? It should look like crescent kick right into the uppercut (well it looks like two punches but you don't see the rapid punch come out at all). I find triple tap -> qcb+C to be easiest but I think I already told you that.
While I press the same button three times, I think a suitable alternative is to drum A~C~A, or C~A~C then do the qcb+punch hold button buffer. Press the three punches as he's landing from the crescent kick or dp.