Will my visa be valid for 3 months from entry or will it state dates only that I put on my application?

Hi, just look at the "Enter before" on your visa. The date behind "Enter before" refers to the expiration date. You should enter mainland of PRC before 24:00 on the exact day of expiration.

I think you just talk about the "Duration of Stay". It is counted from the next day after entry. For example, the date behind "Enter before" is September 15 and "Duration of each stay" is 30 days. If you enter PRC on September 1, then your duration of stay starts from September 2 and ends on October 1.