ISSUES ABOUT DOUBLE ENTRY

Hello!
My name is Rika from Indonesia.
This is my specification:
Category: L
Enter before: 07 Jan 2016
Issue date: 07 Jul 2015
Entries: 02
Duration of each stay : 030
Issued at : Jakarta.

In my condition, I've already travel to china last month on July 17, 2015 with 1 entry only (Jakarta-GuangZhou-Jakarta).

SO, since I'm applying double entries from beginning and I already use 1 entry on last July.
Do I still have available to go to China with this visa? (because my last month trip to china is 1 entry only)?
If I still available to use it, How much time I can stay in China?
Then when will it be expired? Is that okay to fly to China on this last September or end of December?

And if I want to go to Hongkong, Macao & Shenzhen, is that okay if I only have 1 entry Chinese Visa?
For Hongkong & Macao we need to apply special entry permit or?
Is that possible to buy Jakarta-Hongkong-Shenzhen-Hongkong-Jakarta ticket with condition that I only had 1 entry chinese visa?
Thanks
Regards,
Rika