I'm not familiar with mortgage rules in Canada, but assuming they are the same as the US....
I like putting 20% down. PMI is expensive and isn't tax deductible like the interest portion of your mortgage. In order to make investing the better option, your investment has to earn more than the amount of the PMI plus the interest you pay on the extra money you borrow. Keep in mind you will still have to put some money down, so you won't be investing the entire 20%.
When you are searching for mortgage rates you should be able to get different rates and PMI amount for verying amount of downpayments. You will then have to see what the PMI is costing you per month and see how that compares to your expected return from the investment. Remember the % you save from not having PMI is GUARANTEED and the % you expect from investing is not. Also, this will likely be somewhat short term, as once you have 20% equity in your house, you no longer have to pay PMI.
For #2, I think monthly fees are a turn off for some buyers, but when you are looking at condos it is often present. I think it downgrades the resell some, but do you get anything with this? Is there a pool, central office, private party room? Some of these things could help with the right buyer.