Chinese Citizen Wanting to Travel to Dubai

Hi I'm a Chinese Citizen, and am travelling to Africa (Tanzania) for business, how ever want to do a stop over of 3-4 days in Dubai, like a transit for 72hrs- 96hrs

1. Can I get a Visa on entry in Dubai?
2. If not, which kind of visa should I apply for which is the easiest to get?
3. Is it easier to get a Visa through a local Chinese travel agent?
4. Im based in Shenzhen, where would be the best place to send my passport to get a visa as I don't want to travel to Beijing?
5. How long will the Visa take using mail service?

Thanks in advance, and look forward to a speedy response.

Miss Wang Na