Try entering "57BYGH115-003 " in your google search. That usually gets you several web pages where the specfications (voltage, amperes etc ) are shown.
In your Arduino IDE try the menu File - Examples - Stepper - One revolution. There is the code fo one stepper. You only need to replicate the line defining the Stepper varaible (with a new name) and one call to each steper variable's move at different speeds. I also suggest you Google for "Arduino Stepper nonblocking " to run them simlultaneously.
Running at max speed depends on the load, and a bit of tweaking the (software) acceleration and driver current "curves" (if the DQ-542MA supports that)