16-bit is necessary in two situations:
1. When you're working in stupid ProPhoto RGB from stupid Lightroom. I'm very pleased to say this no longer applies to you.
2. When you're working on a very hazy photo, eg strongly backlit at golden hour or whatever. This might apply to you from time to time.
But most of the time, 8-bit is completely perfect, and 16-bit is unnecessary overkill.
And don't forget that you foolishly bought a very small Mac (hard drive size I mean) so you're going to be constantly struggling with space and performance issues. And as 16-bit files are twice as large as 8-bit files, you definitely need to stick to 8-bit as much as you can.