I'll be flying into the Philippines in Manila, and probably won't have a cellphone with me (scary, huh?). Can I buy a cellphone and sim in the airport, near the international arrivals?
Not in the terminal itself but there are many cell shops here. If you need to contact somebody as soon as you arrive then maybe ask a porter or a fellow passenger Then pay them a small amount.
You can also get a taxi to take you to a close cell shop or a mall. You can also walk out to the road to catch a bus or jeepney to do the same thing.