That also works, but you might need an SD card for the download. You could send the file, but it would make for a big email attachment and would be clumsy to Bluetooth. The usual way is to share a store link, but if your pal doesn't have the allowance left on his data cap you could install by passing him the download over usb or bt. So long as he has enough data allowance left to connect to the store to confirm the purchase, and you pass him the latest version, he then has nothing to download once purchased which is cool. Might be easier to just let him tether to your phone's internet and download it that way though, isp allowing.
Everything covered?