Best way to import analog video tape to Mac?
I recently did this type of project with a similar Sony Camcorder that didn't have a USB interface.  

Here are the parameters (constraints) of the equipment we're working with:


Audio is stereo/mono - left and right channels
Video output (as stated) is either S-Video or component - both of which can handle up to 480i (in the US).  IMO, color was better on the component, but YMMV.


What's important to note here is this is the highest quality that will be achievable.  You won't be able to convert this to HD quality simply because the source isn't HD quality.


  What device and/or software should I use to transfer and convert the
  videos into digital format?


I used (and highly recommend) the Elgato Video USB Capture.



This was a plug-and-play device.  The included software was extremely easy to use.  When I used it, I was on Yosemite (10.10), however, I don't see any reason it wouldn't work with El Capitan or Sierra.


  What target video file format should I choose to preserve quality and
  maximize flexibility?


Your best bet would be to use H.264 MPEG-4, which the Elgato supports. From it's Wikipedia entry: 


  As of 2014 it is one of the most commonly used formats for the
  recording, compression, and distribution of video content


H.264 MPEG-4 is a format that's commonly used for Blu-Ray (DVDs) and for Internet services such as YouTube.  This will give you the highest amount of flexibility at the best resolution possible.

As far as audio, the Elgato Video Capture samples at 48 kHZ at 128bits which is considered "professional grade"


  The standard audio sampling rate used by professional digital video
  equipment such as tape recorders, video servers, vision mixers and so
  on.


This is a rather inexpensive setup that worked extremely well (from personal experience).  It took me just over a week (about 100 tapes, not all were "full") to digitize everything.  But once that was done I was able to make backups to both HDDs and DVDs.