Layover in Guangzhou

Yes, you do. Every time when a passenger wants to exit the airside (transit) area she/he has to apply for a temporary entry permit. The good detail is that you have a long layover and you will also be able to present your accommodation booking confirmation (as a printout please), so the airport officials will issue to you a temporary entry permit almost for certain. You should just apply for a permit immediately upon your landing in Guangzhou and this application is for free.