1996 Civic SI Coupe - Idle Problem/Heating&AC Problem!

Hi Everyone. I jsut recently bought a 96 SI (5 speed) and dropped a used
engine into it as the previous engine was seized (long story). I just put
it on the road and all is well (so far). Two (minor) problems i've
encountered a High Idle speed when slowing/stopping down and after
releasing the clutch. This happens after the car has been driven for a
while. I've read other posts and have become sort of familiar with the
IAC Valve. The O2 sensor on the car is new. Could the IAC be the
problem? How do I remove it and should I replace part of it (which part)?
Should I replace the whole thing? Should I clean it? How? !!

Problem #2: The heating controls are all messed up! When I select the
button for the windshield (front) defrost, the vents from the dash start
blowing, when I select the vents only, the front windshield defrosters
start blowing!! What could be the cause of this??

thanks for any and all help you're able to provide!
Aly