Do NOT be surprised if/that suppliers/manufacturers do not respond to e-mails. It is and can be simply overwhelming, especially from hobbyists who buy surplus stuff and then drive the factory's nuts looking for free tech support.
If you want/need info, CALL THEM and ask for the engineering dept. Have your questions ready and don't "tire kick" and do too much B/s'ing - they are usually quite busy offering help/dealing with paying customers to do too much "charity" work. Will they help? Yes. Do your engineering for you? Not usually unless you find someone who's bored and/or not too overworked/underpaid.
The voltage of the P/S is pretty much going to determine the speed. The current output is what you're looking for/at for your case. You don't simply add the total current as this is not realistically going to happen - that is, for all your motors to ask for/draw peak current simultaneously.
A reasonable assumption is to use 60% to 70% of the total peak possible current draw. Having MORE current simply means that you can't/won't stall the motors or overload the power supply EVER. You might pay a bit more for TOO much current capacity in a P/S but, recall, you can't "shove" current into/thru a motor. You can only draw what the motor asks for.
Most P/S's do have current limits built in. Hence, if you try to go overcurrent, the thing will either shut down or fold back the voltage to reduce/limit the abiltiy of the P/S to not go over current.  |