After repeating the sentences over and over to check my natural intonation, I have come to the conclusion that the intonation on the "please" is very similar to the 3rd tone in Mandarin. It has a slight falling then rising sound. Also, in spoken English, there is very little, if any, pause at the comma in "Could you repeat that, please?" It will just sound like 5 words said at about the same speed.
once you are used to using the "please" at the end of a polite question, it will just come natural. "Could you hold the door, please?" "May I have a refill, please?" etc.