I have a little cousin overseas and wants an iphone, it is cheaper here than over there, if I bought the iphone retail price and mailed it to her would it work overseas for her if she went to her cellphone carrier
This is possible, however, you will need to purchase an unlocked version of said phone.
The only place to buy an iPhone completely unlocked is on their website or in a real Apple Store. iPhones purchased at authorized resellers are not truly unlocked, meaning they will be locked upon inserting a SIM card.
1) it would need to be unlocked if purchased from Koodo. I would just buy it from Apple for her
2) It depends on her carrier overseas. If it is a typical GSM/3G network where other customers are using the iphone with that carrier then it will work. However LTE maybe not, depending on the model and country