Is the 10-year visa a multiple-entry visa?
If it is a multiple-entry visa and I plan to visit China a year later after my first trip, do I need to enter the second trip information on the application form? Do I need to send the Chinese embassy a copy of the itinerary for the second trip?
It would not make any sense to provide someone with a 10 year single entry visa. It is definitely going to be a multiple entry visa.
You didn't mention your Nationality but for the sake of this source if we assume you are from US
Most U.S. passport holders eligible for Chinese short term business (M) and tourist (L) visas will be issued multiple-entry visas valid for 10 years. In order to be eligible for 10 year visas, US passport holders must have more than 1 year validity remaining on their passport. US passport holders with 1 year or less remaining on their passport will be issued a China visa with less than 1 year validity. The Chinese Consulate will make the final decision about the length of the visa. Once a 10 year visa has been issued, the validity of the visa does not expire if the holder renews his/her passport. The visa holder can travel carrying the old passport with valid Chinese visa along with the new passport. The cost for the visas will remain the same.
In accordance with a 2014 China-U.S. visa arrangement, U.S. citizens may be eligible for 10-year multiple entry visa. The remaining validity of the U.S. passport must be over 12 months.