I may add more pics later when I'm sure these want to stay.
The quick release is a nice feature when you want to do free motion. You just pop the button up and it releases the tension on the pressure foot. The old fashioned way would be to turn the nut at the top like on my 15-75 Singer and when you are done you have to re-adjust the pressure. That info should be in a manual. It isn't hard to do but is sure is a nuisance if you want to go back and forth from free motion to regular sewing.
I love my little 15-75 but she doesn't have a pop up - maybe some time I will put one on just to soup her up just a little. Her feed dogs drop under the machine - a lot of the Japanese machines have buttons or a knob to drop the feed dogs. Some machines do not have the ability to drop the feed dogs.