Canada does have a DL exchange program with certain countries, such as UK, Germany and more. If he is from one of those countries, the registry can look it up, they will do an equal exchange.
If he's not from one of those countries, he has to take the test. Since AB has a graduated DL program, they will let him take the written test right away but they will not let him take the road test unless he can prove that he has a DL from another country. For this, they need his old license plus a translation if it is not in English or his old license and an international license. The registry will send them to the AB government and they will take 2-4 weeks to approve him to take the road test. Get the phone number from the registry to call the AB government to check up because they will not let you know when it's approved.
If they are satisfied that he had his license for more than 5 years, they will let him take the advanced road test and get a full license right away. Otherwise they will only let him take the basic road test and give him a GDL license for 2 years. The only difference being that you lose GDL license for fewer demerit points than normal and you are allowed zero alcohol level, not even one beer. After 2 yrs. on GDL license, he would be able to take the advanced road test for a full license.
If he didn't have a license before or he can't prove that he did, he would have to take the written test right away and then wait a year to take the basic road test for the GDL license. With just the written test, you only get a learners permiit and are not allowed to drive alone.
As for the old license being sent back to old country, that varies. They are supposed to but some provinces do it and some don't. When my German friends moved back and tried to find out where their licenses had been sent so they would not have to pay to get a new one, they were told that it's not very common for them to be sent back. When they called the AB government to ask where they were, they were told that the AB government has better things to do than to have a full time person mailing peoples DL's back.