I'm sorry I don't understand
Both five sentences above will be used under talking with strangers rather than people who you actually know. These are very polite expression and are in most case inter-changeable. However, it will be odd to talk to someone who you have already known with that level of politeness. It might work for Professor(s) / leader(s). Talking with friends or family will use more colloquial expression like

"稍微慢一点" "等一下，你说得太快了"