Leading Power Factor effects on electrical System
Keeping power factor in leading shows more KW &amp; less KVA? Is it
  correct or not.


This is incorrect. If the real power load is 10kW, at unity power factor the kVA is 10kVA. If PF = +/-0.95, on a real load power of 10kW, kVA is 10.52kVA.

Leading PF is caused by a net capacitive load and the effect of it is the same as a lagging PF (inductive load); the supply current is higher than for a truly resistive load.

You can keep PF leading (or lagging) as long as you want but it isn't an ideal situation because some electricity companies have a policy to charge you for use of reactive power in order to supplement the cost of putting bigger cables into their feeders to factories - higher current means bigger cables.