I must tell you this, that everything we discuss here is a calculated speculation based on GCMS data of different applicants etc.
Nobody can, even the senior most member of the forum can 100% predict what CIC does, when and why correctly. But as our tried speculations are correct in most cases so we carry on the wait depending on them. There are always different cases.
Now to your question my friend, as per current information from candidates, eligibility is being checked in NA2 stage for sure. In NA2 stage the case analyst recommends eligibility as "recommended passed". The final approval of eligibility and all other checks is done at IP2 stage by the Visa Officer, who checks the file for one last time and approve it and issue a PPR. Now mostly Visa Officers just check the recommendation and simply pass the case, its more of a formality here. But some Visa Officers can call Employers for verification at this stage, this may be due to some doubt they find or sometimes as a random quality check (though this rare). Some VO are cruel and may also reject files at this stage, as in some cases the case analyst is not sure about eligibility and recommends eligibility as to be reviewed etc. i hope this clears your confusion.
Also as per latest data form GCMS,Ottawa is issuing IP2 to mostly approved files. So this good news for Ottawa people.