Airlines apply the ID discounts in different ways. Normally the base fare is discounted by the percentage indicated. Sometimes the discount will only apply to the full economy fare, other airlines will discount lower yield fares.
Taxes will normally be charged at full rates, and the surcharges are handled according to each carrier's policy.
Your staff travel department should be able to give you the information, or if you have access to airline's Fare Quote system you should be able to calculate the fare using the appropriate discount code such as ID90N2.
There are restrictions on travel dates, and travel is, or may be, subject to load. You can be denied boarding or offloaded at the last minute, and again, dependent on your airline's policy, you can be offloaded at an intermediate stop if there is weight restriction or commercial passengers wanting to board.
I do not know what EK's policy is so the foregoing is general only and should not be taken as gospel!