1) On the ESS Leave Request Application there is a Tab for Time Accounts which displays the Quota Overview (Entitlements) for the employee. When is the entitlement updated, when the employee enters a leave request/absence or when the Manager approves the Leave .?
Ans :it also shows when you request, and of couse final update is after rptarqpost in pa30, but in ESS it ll show the deduction when you send the request, you can test this
2) Can we have Cost Center field on the ESS Leave Request by any configuration?
yes its available in Sm34 > VC_PT_FIELD_SELECTION_LEA, LEA
And you can select cost center and assign it to the particular absence you want
Check define field selection in PTARQ
3) If a leave request has to be modified and the employee is not available ,i.e if he is on leave , then who will do the change ?
time admin in PTARQ
4) Can an employee or Manager edit/change Timesheet request after it is Approved?
yes employee can edit it if you allow in CAC1