fitting a Fire sorround,

Hi, I have a granite hearth and back surround with a wooden mantel that i want to fit to save costs so the plumber can fit my gas fire
http://www.fireplacemegadeals.co.uk/gbmantelsrossfireplacepackage-p-306.html
the hearth and surround weigh a tonne, and the mantel is made of veneered wood.

as i see the mantel. I need to put the hearth down first...
then the surround then the mantel..

Can i get your advice (newby style answer please. or i'll keep coming back for more on how i achieve this.

My guess is.
have a mortar bed to put the hearth on ( if i'm right what ratio) level it and let it go off.
then add the surround on... glue it to the wall?? with what if so.... do i then seal it? if so with what...

then add the mantel.... ( should be straigh forward but i can't see anywhere on the mantel to put a bracket.. or something similar.. ( without it being seen) any ideas?


Thanks for all advice.....
Mark

anyone? or am i posting in the wrong area?