Yes, it can be used as an MP3 player by copying MP3 music to the root directory of the recorder. 

Yes, it does come with 3.5mm headphones. 

Yes, the hidden voice recorder device comes with a 3.5mm port, charging and data cable, which allows you to connect to Windows/Mac computers and Android/IOS smartphones to realize bi-directional transmission. It also comes with wired headphones, you can use headphones to listen to recordings directly on the device, and supports selecting previous/next track for basic playback and volume control. 

Yes, this voice activated recorder has a recording time synchronization feature that automatically saves the file name of the recording as the recording start time. 

Yes, this 128GB pen recorder is equipped with a DSP noise reduction chip that intelligently filters out ambient noise.