1. Within how much time does the visa office at New Delhi returns the passport back?
I don't know
2.When I applied for PR way back in 2010 my family status was single and now also it is single, but my family is planning to get me married off once I received my PR visa stamped on my passport, so once I received my visa, how can I inform the Visa office about change in my social status informing them that I'm married, and if at that stage I want to add my spouses application along with mine will it be possible and what effect will it have on my own visa and how much more time will it consume, since my spouse to be needs to apply for a passport as well as we need to have a marriage certificate for getting the passport issued also.
Be very careful with this. If you get married before landing, your visa will become invalid because your family composition has changed. Immigration is very strict about this. If your passport is now with the visa office and you absolutely want to get married before you land, you must notify the visa office immediately that they should not issue your visa because you are about to get married. You have no choice about adding your wife to your application if you marry before landing. You must do it. It will delay your application but you do not have a choice. Your other option would be to delay the marriage, go and land quickly when you get the visa, come back, get married, go back to Canada again and apply to sponsor your wife. As a PR, you must be residing in Canada to sponsor. To sponsor from India could take 7-9 months. Your wife will most likely not be able to get a visit visa to come join you in Canada before her sponsorship is complete.
3.if i want to marry a lady who is already a single mother to an adopted kid, what all is the process, kindly reply please as im too much worried now?
You can add both of them to your application now or sponsor both of them later. It needs to be clear that she has full custody of the child. If there was an adoptive father as well, an ex husband of hers perhaps, he either needs to agree to the immigration of the child or she needs to show she has full custody.