Some questions about the smoke procedure in A320
 

For 【QRH】SMOKE/FUMES/AVNCS SMOKE
If AIR COND smoke/fumes suspected, why we need to turn off the APU BLEED？

For 【QRH】REMOVAL OF SMOKE / FUMES
Why we need to turn PACKs OFF？ For the EMER CONFIG, it can be closed？
For the EMER RAM AIR, it said that "At FL 100, or MEA-MORA, it is possible to open the RAM AIR valve when ΔP is 1 PSI or below."……Why it is possible？ Under which conditions it cannot be open？