You said your wife is pregnant, which is very similar to my case. Did you guys do an upfront medical for your wife? We were told we can put the x-ray on hold and go ahead to do the upfront medical. After all the other results are back, the medical clinic told us they cannot submit the medical report to the CIC anymore, because the x-ray is on hold. This is very strange because I called CIC before and they said we can submit the report while putting the x-ray on hold. I just want to know what your situation is on this upfront medical issue.
And one thing still confuses me, why can't the person being sponsored go out of Canada for a short period? Don't they have to go out because their 6 month visa need re-entry to start kicking again?
Supposedly we will have the medical upfront because a lot of experienced people here in the forum did that although not in the same situation. When we were gathering the documents, a friend of mine referred us to a consultant, we met her and discuss everything. After hearing the price for her service, we consider to do it by ourselves. My wife applied here in Canada without asking any help from other people so I believe that we will make it the same as well.
The consultant said that instead of having a medical upfront, we should wait until my wife gives birth. When my wife gives birth (which is anytime soon) we will get an appointment plus we will submit additional family information stating that we have a child already.
Many people here did the medical upfront too, but in the end they need to have te medical redone again because its already expired so they cost them doubled.
With regards to your other question, as far as I know, they can extend their visa here without exiting somewhere as you will file your application INLAND.
Let's wait for the others to comment regarding your questions.