Marcus from England - Travelling to Guangzhou then Singapore and Back to Beijing.

Hello, I am a British passport holder. I am travelling to Guangzhou on a business trip and have an invitation letter from a business there,

1. do i have to make accomodation arrangements as well before applying or can i sort accomdation when i get there as the company have told me they will sort that out.

2. as i am leaving Guangzhou to go to Singapore for another business trip will i require a pass to re-enter again after to go to Beijing for a leisure visit of my frineds working there who will put me up for a few nights?

3. Do i need to disclose that i will be re-entering or does my entry permit which i should get from the 90 days invitation letter from the Guangzhou business still cover me for flying in and out during that time?