If you have driven in SL for more than 5 years (but I also remember this as 3 years) - you don't have to do G2 after passing your knowledge test. Meaning you do the knowledge test and then hire an instructor, learn how to drive here (because there are many differences) then take the final exam which is the G exam. Once you pass, you get the full license.
To get the DL extract, you need to go to RMV in Verahara, ask for an International Driving License Extract and they give you a paper signed and sealed by RMV with license acquired and expiry dates. You should take this and go to Foreign Beaurau in the Seyaln bank building in front of WTC. Get this paper attested (they sort of give you a confirmation that it is a true copy) and bring this to Canada. Once you go to take the exam at the Drive test centre of your choice, provide them with the DL extract and let them know you intend to take the G exam directly after the Knowledge test (G1).
Hope that makes sense. I followed all of the above and did my G1 and waiting for the final test. Good luck