repairing flue/firebricks, cast iron fireplace

[Philip Brabon]

Hi
I have a very old cast iron fireplace and had the chimney cleaned recently .At the top of fire bricks there is a iron plate and behind that the sweep removed a few old corrupted fire bricks. I now need to replace these firebricks but the sweep left the iron plate flat against the rear wall. The questions I have are:

1. Is this the right place for the cast iron sheet to remain
2. can I replace the bricks at back of iron plate easily
3. The cast iron plate seems to also hinge more forward of the grate as there are hinges there for it

I was going to replace the firebricks myself but are now faced with the query of the cast iron plate
Any help would be appreciated

 

[Tigercubrider]

pictures would help