94 honda civic, hops in reverse, please help!?

i just had the clutch replaced and one of the same problems i had prior to the clutch replacement still occurs, which is when i put my car in reverse it still crackles/grinds(sometimes) and it hops/bounces(a lot) just as i let off the clutch as i give it little gas. right now i can't imagine not "riding" the clutch in reverse due to it jolting back(i know that "riding" the clutch is not good but i can't risk running into something/someone when my car does this!). lately i've been questioning the rapid decrease of the RPMs just as i disengage a gear into another gear or completely disengaging into neutral and for some reason i'm guessing it may be the IAC? my few questions will be: is it normal for the RPMS to fall quick as you're disengaging/engaging into another gear? is there a solution to the hoping in reverse? and an off subject question: why does my a/c not blow hot air when i put it all the way to red? thank you for the answers, all appreciated!