Eccentricity Value in Response Spectrum Cases and drift checking

[AqibUsmanMoosa]

Dear all,
My question is that
What value of Eccentricity we put in response spectrum case

a. .05
b. calculate from ratio of story maximum and average lateral displacement
c. zero as default ( as i assumed that 5 % is already included.)

To calculate drift, i should check the response spectrum case drift value directly from table or summary report or make some other load combination to check the drift. I heard that we have make a load combination of type MODE with scale factor is amplitude and combination is SRSS.

Thanks