1. I meant for voice traffic, there is no differnce in the voice quality of the end user(codec is the same) in either technology , there is no benefit for the voice user to go 3G.So keep the two technologies independent in order to maximize their capacity (NO IRAT),Use 2G only as a safety net to save the drop due to lack of 3G coverage
3. This is to maximize the 3G coverage in cell selection . When you put 3G access parameter to floor meaning,set the access paramter to min vaule allowed in your system example, ECIO >= -24 and RSCP=>= -118 ,
This way you made sure the only case the user will go to 2G is when the 3G has no usuable signal
Thanks