Second stepcraft

Hi i have the stepcraft 600 lpt with dremel 3000 on it, i want to take and one stepcraft 2 840, what did you recomend me to take stepcraft 2 lpt or usb? What spindle kress 800 or 1050?and in my stepcraft 600 lpt i have the winpc nc economy , can i play and the two stepcrafts from one pc? Thanks, your advice they will be very helpfull!