Power Factor Correction

We have factor control system employing 4 capicators of 40KVAR each, in our pharmacuetical plant we have mostly AC motors ranging frm 1KW to 40KW, what I see on the pf controller that pf indicatios at times go into negative range, i believe that this may be due to capacitance on line is more than required. Electricity bill shows average pf 0.72 for the month.
my questions are 1. shall a combination of 5, 10, 20, 40, 40 KVAR be all right, so that controller can bring required capacitor on line, in that case shall there be a sequence to be followed like mentioned above or controller can bring anyone needed on line. 2. Our main distribution line current goes upto 300A, currently we have 200/5 CT giving feed back to pf controller or should I be using 400/5 current transformer 3.What happens if capicitance on line is more than needed, is negative indication of pf on the controller related to this.
4. How do we calculate KVAR of the inductive load, by knowing KW, pf, I and V
I may be asking basic questions because my trade is Mecahnical Engineering. I think with your help I can have an understanding of the system.
Best regards
Hamid