http://en.wikipedia.org/wiki/EBIDTA
EBITDA as a line on a company's income statement is used as a reporting number in calculation of relative profitability. (EBITDA relative to debt, interest, competitors etc)
It is used rather than the bottom line number because it is a raw measure of how a company is doing, what profit if any it is generating from business.
The other bits can be a bit distracting or could mask true performance. Interest might be high because of acquisition debt unrelated to current activity. Taxes might be low because of carried forward losses, depreciation might be low if the assets are old.
Normally rent would be above the EBIDTA line (the money was paid and used in the period), depreciation on an owned asset would be below this line (the money was paid out long ago and the asset was accounted for at the time)
Amortisation in the context of a mortgage wouldn't show up on an income statement - it is a balance sheet transaction.