Visa on arival from Hongkong to Shenzhen at the border of Luo Hu

Yes, you ar able to get an on-arrival visa to enter and stay in Shenzhen for less than 5 days. But the visa is only valid for a 5-day stay in Shenzhen. If you plan to to go to Guangzhou as well, you should apply for a China visa from the visa office of PRC in Hk in advance.

1. You said that visa on arrival valid use for a 5 days stay in Shz. Can I use the visa if I stay in China:
- from HK I will go to Shz, apply VOA at the border of Luo Hu (11 Aug)
- in the same day I go to Guangzhou. Stay in GZ 11-13 Aug
- Back to Shz 13 and stay until 15 Aug.
- 15 Aug, back to HK.
So, I stay in GZ and Shz is total 5 days.

2. How about the time: The latest train from Shz (Lou Hu Station) to Hongkong?

Tq.

1. Unfortunately, the 5-day visa at Luohu port is only valid within Shenzhen. It cam't allow you to enter Guangzhou.
2. I think you mean the last train from Luohu of Shenzhen to Hk, it is at 00:40.