replacing your exixting hard disk into a new a1200 will see your new a1200 be exactly how your old one was...assuming whatever the fault was that killed your a1200 didnt kill the hard disk too of course.
you will still be able to use your existing gold card and accelerator exactly as you did before and WHDload games will run very nicely with your accelerator card.
as for the monitor, you will need a scandoubler/flicker fixer to play amiga games on pc monitors and they rarely go below £100 on the bay.
if you realy want a monitor and not to use a tv i would suggest picking up a commodore 1084 or phillips cm as they display the native modes for the amiga during gameplay, you can often pick them up here in uk very cheaply.
hope this helps