One more question, me and my wife are both CA's working with Big4 in different fields.
1. When I create my profile, do only I have to apply in the job bank or my wife's resume can also be floated?
Only the principal applicant can join Job Bank. That said, Job Bank is pretty useless at the moment (the service is still under construction). Joining Job Bank is just a formality you have to go through in order to submit your EE. You will almost certainly NOT find a job on Job Bank.
You and your wife can both try other job search sites, however. (You have more chance with other sites than with Job Bank, but the prospect is still bleak.)
2. If my wife gets any job opportunity, would her additional points be counted in mine?
No.
If your wife gets an LMIA supported job offer (and you do not, and you also don't have provincial nomination), then your wife would score more CRS points than you. In that case, you would create a separate EE profile with your wife as the principal applicant, which would have a higher CRS than the original profile, and will get ITA very quickly.
3. Considering that both of us have different experience, would it be advisable that we file 2 separate application, 1 in which I am the applicant and 1 in which she is the applicant? So that incase her skill set is more in demand in Canada, she gets the ITA.
Your skill set has absolutely nothing to do with whether or not you get ITA. The only thing that matters is your CRS.
You should use the CRS tool (http://www.cic.gc.ca/english/immigrate/skilled/crs-tool.asp) to see whether you or your wife get higher CRS. Whoever has the highest score should be the principal applicant.
4. Further to question 3, if 1 of us gets an ITA, can 1 application be withdrawn subsequently?
Yes.
Regards