One-day trip to Kinmen from Xiamen

My wife and I will arrive XM from Los Angeles on Oct. 23. We wish to revisit Kinmen after 50 years. We wish to know first sailing time from XM to Kinmen, and last sailing time from Kinmen back to XM on Oct. 24. We have booked the Tegoo Hotel in XM for the night of Oct. 23. We also wish to know which ferry terminal in XM we should go to avoid the rush of tourist groups. While in Kinmen, do we need to hire a guide in order to visit as many former war fields and installations as possible? We don't care about shopping. (FYI, I was invited to visit Kinmen as a journalist in 1963)