Hi rohitcan,
For 2, upon re-reading it, it definitely says that this requirement applies when there are dependent children. So, it seems that proof of income is not required. Just a "promise" that you will provide for your spouse. Info from: http://www.cic.gc.ca/english/information/applications/guides/3900ETOC.asp. Relevant para:
- sign an undertaking promising to provide for your spouse or common-law partner's basic requirements and, if applicable, those of his or her dependent children,
- prove that you have sufficient income to provide basic requirements for your spouse or common-law partner's dependent children. To do this, you must provide documents showing your financial resources for the past 12 months. This requirement applies only when dependent children who have dependent children of their own are included on the application.
However, I would advise having a proof of income. It will only strengthen your case. You could submit an application without a proof of income, but that *may* cause delays in your case.
For 3, yes you definitely can visit for a short period of time. In fact, while the sponsorship application is in process, your spouse can come visit you on a Temporary Residence Visa.