It shouldn't damage the equipment. But it will probably not work properly.
what is the basis of Your
If you have the right test equipment amps are the easiest to measure. A slip over the wire amp meter is easier to use than a clamp on amp meter. The other two values have to be measured by using test leads from the test equipment.
A unit of electrical equipment is designed for operation at a certain voltage - or within a certain range of voltages - i.e for 5 volts, 12 volts, 120 volts. 220 to 240 volts. Originally the UK household alternating current supply voltage was specified at 240 volts or, more precisely, 240 volts RMS +/-6%, running at a frequency of 50Hz.Some time ago, to allow harmonisation across Europe, the specifications were changed to 230 volts RMS +10%/-6%, also running at a frequency of 50Hz.Thus the mains supply voltage will remain within European Union norms (standards) even if it varies between an upper limit of 253 volts and a lower limit of 216.2 volts. So, because 208 volts is lower than the minimum range of a standard 230 volt 50 Hz supply, it is not safe to assume that any equipment which has a rating plate saying that it should be powered from a 208 volts ac supply can be used on a 230V ac supply without causing any damage. Such damage might affect the equipment itself or its surroundings or its "human" users... If the Asker could use the discussion page - by clicking the Open Discussion button shown below this answer - to tell us exactly what the circuit is, which "demands 208VAC single phase", that information would be interesting to know. Then, maybe, a much more helpful answer could then be given here!
No
If you use this formula W = Amps x Volts you will not need any tools. Using equipment nameplates will give you both values. If nameplates are inaccessible then you need a volt meter and an amp meter to obtain these values.
what is the basis of Your
Yes you will.Each piece of equipment is designed to work on a specific voltage. Wrong voltages applied to it will destroy the equipment.
30 volts of ESD
Yes it coudl damage equipment. Check voltage rating on equipment. However, there should be an adjustment somewhere on the generator to set the voltage properly. Also make sure your meter is calibrated. Check a known voltage source such as an outlet and compare readings.
No, that type of equipment has to be designed to work with a standard 1.5 v battery, which has a voltage about 0.9 to 1.6.
and breakers that can only hold up to 250 volts
48 volts is a convenient safe voltage to use, and telephone systems use a positive earth connection to minimise electroytic damage ot cables.
At 120 volts you can operate any equipment up to 1200 watts. At 240 volts you can operate any equipment up to 2400 watts.
If the manufacturer specifies that a certain voltage is needed for their equipment, then that is the voltage that must be applied to it. To do otherwise may ruin the equipment and void the manufacturer's warranty.
This action takes inverter equipment that is explained in the link below.
The label rating of 125 volts is applied to 120 volt equipment. It is an insulation rating of the device. Like wire with ratings of 300 volts, 600 volts and 1000 volts these are the highest allowable voltages that can be applied. A wire that is rated for 300 volts is good for 120 volts, 240 volts and 277 volts. At test research facilities, equipment is tested to destruction. The label that is given to devices as a result of the tests is the highest safest voltages that can be applied to that particular device. So when you see a device that has a label stating that it is rated for 125 volts it means that any voltage under and up to 125 volts is safe to apply.
Amtraks newer system, from New York to Boston, is 60 cycle 25,000 volts. The system south of New York is 25 cycle 13,000 volts.