Are all of the machines capable of using the spindle, laser and 4th axis?

Yes, you can use all of these attachments on each of the machines.  However the small size of the STEPCRAFT-1/210 might make it tough to use the 4th axis with longer work pieces. Additionally, the 210 has a limited 3″ Z height, which does not leave a lot of vertical travel and will limit the diameter of material that you can use on the machine.   Additionally you really need a T-slot when using the 4th Axis so you can adjust the tail stock for the length of the work material and the 210 is the only machine that does not have a T-Slot option.