I have few questions regarding these two forms.
1) Point 3. Your Net Personal Income
12-month period starting
Should I write 12 month period that ends on the day I send my application?
As heatherusa have said, put the 12 months prior to the month you send your application in.
2) I don't have any previous undertakings and this is my first sponsorship application. What should I write in details of family members and persons included in undertakings in effect or not yet in effect (Point 5.B)i) to point 5.B)iv)?
This part was pretty tricky for us, too. So basically if you're just sponsoring your wife, this part should look like this -
4. 1 - that's already put there.
5. A) 1 - that's for your wife.
The rest just put zero except for number 7. Here you put 2 for you and your wife.
Point 8. Have you resided in countries other than Canada?
I came Canada in 2002 and before that I was living in India and I never lived any other country than these two countries. Should I write all addresses I was living in India before coming to Canada?
And as mentioned by Raymasood as well, just put the address where you lived in India before you moved to Canada.