it depends on the stamp then you will know how many stamps you will need
how many first class stamps does it take to mail a 4 oz letter and package
this would depend on the weight of the package
80
23-30 stamps depending on the weight of the package.
It depends on where from, the weight of the package and what transport is used.
For a 5-ounce package, you would need to use enough stamps to cover the postage cost. In the US, the current rate for each additional ounce in a package is $0.20. Therefore, you would need to calculate the postage cost based on the total weight of the package (5 ounces) and then affix the appropriate number of stamps to cover that cost.
You need 1 stamp to mail a letter/package throughout Canada
That will depend on the weight of the package and the postal class (e.g. parcel post, media mail, priority) of the package.
You would really have to know the weight and dimensions
The answer depends on the size of the cards. It could be just one large package.
"Regular size package" is a very nearly meaningless term. If you really want to know, go to your post office. They can measure and weigh the package and give you a definitive answer as to what the postage will be.