My Bernina has a slide on the front to control the speed of the machine so I have variable speed control. When I was teaching my sons girlfriend how to quilt I set the speed a lot slower because she was not used to me machine and was nervous about it going fast. I will slow it down some when using some of the specialy stitches or alphabets. Occasionally I will slow it down for the embroidery unit too. My older Pfaff had it on the foot control, though only 2 speeds. When you are just starting out you probably don't want your machine going 90 miles an hour.
The needle up/down is one feature I just love. You can set the machine to always end with the needle down, that way if you are in the middle of quilting and you have to turn the corner or leave the machine or whatever the needle is automatically down so you can start again exactly where you left off. Too many times I ended up with a little "jump" when I forgot to manually put the needle down when pausing. I have a little button on the front of the Bernina to lift or lower the needle or set it one way or the other.