yes you can use any visa to enter any place.visa are used for visisting countries.
Can not visit Canada without some kind of visa. There different types of visa's depending your reason for visiting Canada.
yes
It depends on what country they originally are from. You need to check with Immigration Canada and see if the country of origin is on the Visa required list.
I have UK travel document (blue) do I need a visa to visit canada?
biafra
Yes.
for visit no but business yes
Yes
Canadians do not need a visa to visit morocco
Technically there is no connection between canada and Uk visa processing except that if you have a record your chances will go down a notch. But it is not impossible to have.
I5 DAYS OR ABOVE
No you don't need a visa to enter hong kong but to be safe, secure a return ticket and a hotel reservation.