This sheet says they are 1 amp motors, so 2.5amps would be way too high. Also, they have 7ohm coils(ie 7volts at 1 amp), so 24v might work, but would be a little low for a supply voltage. For best speed, you generally want the supply voltage to be 8 times or more the rated voltage of the motor.
Generally speaking, current flow provides torque and voltage generates RPM.
However, using Ohm's law, a higher voltage applied across the same resistance results in higher current. Thus, at 7 times the rated voltage, you'll have high speed plus high torque provided you can ultimately limit current so that it does not rise excessively and cause stuff to fry.
Recall that you can't "shove" current thru a device - you draw it as a function of Ohm's law. Thus, just because a power supply CAN supply say 10 amps, that doesn't mean it will - current flow is a funtion of the voltage it puts across the load resistance, again pursuant to Ohm's law.
Thus, any current limiting is done by either folding back voltage via the control strategy after the initial "hit" or putting resistors in series with the coils to resistively limit current, again using Ohm's law.
E= I x R.
One MANDATORY to learn equation for the budding DIY CNC'er. Other helpful ones to learn are those that involve series and parallel resistance.
Thats an A3977SED based bipolar board, so 24 volts is nearly the max voltage for your drives. Full winding would be painfully slow at only 24 volts, so run it at half winding. Half winding current would be the same as unipolar current. You can't run a 6 wire motor parallel. However, on many 6 wire motors, you can carefully remove the end cover, find where the coils are joined at the center tap, split them and bring out two more wires. This would let you run parallel. For parallel connection you can normally use 1.414 times the unipolar current.
PS Series and full winding are the same thing. If you wanted to try it, you would use .707 times the unipolar current, but like I said it would be very slow.