When you submit your application you should include 6 months bank statements to show the history of the money (since CIC will want to convince themselves it has not been borrowed).
It's advisable to keep at least most of the funds in the account at all times, since visa office can ask for additional proof of funds statements later on.
They basically want to ensure the money is yours and available when you land in Canada, so if you make any withdrawals you are best to make sure they are only small, easily replaceable amounts.
No problem at all. If they ask at a later stage for statements simply get statements for both accounts and they can clearly see the amount is transferred from one account to the other.
Of course it is likely they will not even ask and that the next time you will need to show proof of funds is landing, but since they CAN ask, it is important to know that you can easily sort the proof if required.