1. Yes you can take travelers cheque but you should check whether it is accepting in Canadian bank or not.
Previously, American Express travelers cheque I have used and fall in complexities at the time of exchanging.
Travelers checque is expensive when you encash it.
2. You should have tickets if you want to buy dollars from bank. but you can buy it from any money exchange without buying tickets.
Now all money exchange ask for visa and PP copy.
3. There is no problem at all. You can carry 5000USD per person. No issue.
one adult person can carry 7k us$ or equivalent CA$ and for infant half, i mean 3.5k us$ in a year. so you can your full quota when you immigrate. [as of 2015 new cerculer]
extra dollars you can keep in different places to avoid risk. BD immigrant police may ask for it and demand bribes.
