VISA for me to visit my friend in China.

My name is Tahiche Rodríguez and I am a Spanish teacher currently living and working in Dupnitsa, Bulgaria. I am contacting your Consular Office because I am travelling to China next July 10th (departing from Italy) and I have a few questions concerning my visa.

1. Somebody will submit the application for me: shall she present any special documents to prove she is doing so on my behalf?
2. If I am travelling on the 10th July, when would you suggest applying for the visa?
3. The person hosting me in Beijing is an Italian citizen invited by a Chinese company: shall I ask him for the details of the original invitation letter of the company (which was submitted at the Consular office in Milan)?

Thank you in advance.
Yours sincerely,
Tahíche Rodríguez Hernández