Can anyone tell me if the engine or engine and box from a 2001 1.6 Marea
will fit into a 1996 1.6 16v Brava and what modifications required to do it
I need to know asap

You might hit some complications with yours being a MK1 and the marea engine being a MK2. However if you have the full wiring loom and ECU's etc then you should have no real problems. Im sure someone will either correct me or confirm this in a short while.

Yes it will fit but the ecu and most of the wiring loom will not be compatible as the marea will have the mark 2 engine (plastic inlet manifold) and yours will have the mark 1 engine (metal inlet manifold) look for a mark 1 engine and stick that in instead its not worth the aggravation of trying to put the newer engine in.