Capacitor in series and parallel to diagnose APC Smart UPS 1000VA
For 2 use a 3300 uF, 40+ V. That is a more standard capacitance value than 2700 uF. And you may find others that are more than 40 V are available and those at 40 V.

For 2 your calculation is correct. However this reduces the capacitance so I wouldn't go that way. I would go with 4 or 5 instead.