Hi Michael,
First, courses are being updated to 2.80, but that takes time of course (especially considering that the 2.80 RC1 is only about one week old!).
When sculpting, yes, you can quickly change to the Smooth Brush by holding Shift. No matter what brush you are using.
So why have a Smooth brush then? Because if you need to do a lot of smoothing, it is not practical to keep holding the Shift key pressed. Also if you want to change some of the brush settings, you can’t do that when holding Shift.
As to your second point: they were probably changing the strength of the brush (Shift+F), not the size (F).
I think you should definitely cover the basics first (the fundamental knowledge), you are not losing knowledge that way. But there is also no harm in watching current courses.
I can highly recommend joining Kent Trammel’s upcoming Class (starting July 30th):
https://cgcookie.com/live_streams/bc1-1908-3d-modeling-with-blender-2-8
Four weeks for any skill level!
Hope this information was helpful.
