yes u do need to get rid of both ecu's mate as the ofab/ofac all runs through the same ecu.. AND YES u will need to have it set up after as u dont know what the mixture etc is set at so do it the safe way and have it set up..
ok i am currently doing this conversion.. i have all the parts i need also.. these are the following..
FRST HEAD ( can fit ERST but need conversion plate and cap for dizzy hole)
FRST INLET (xr2is the same)
FRST BLUE INJCTORS (will soon be beige)
FRST ENGINE LOOM ( OFAB )
FRST RELAYS (FUEL & INJECTOR)
FRST FLYWHEEL
FRST CPS (crank sensor)
EDIS MODULE
FRST COIL PACK
FRST AIRBOX
HERES A VERY VERY HELPFUL SITE ON THIS CONVERSION ASWEL..
http://www.rsbible.co.uk go in the escort s2 section then into EFI conversion..
BTW u will need to wire the relays up ya self as theres some wires u need to add.. (easy tho)

if u need any diagrams or anything pm me and i'll get back to ya.
enjoy mate..