hi there,
the home button and soft key flex cable are obviously under the glass,
if the screen is an original factory fitted it is almost impossible to remove the screen from the midframe to replace, as the double sided tape samsung use is really strong and the lcd is wafer thin,i recently changed my screen and after a couple of weeks the menu key stopped working,i was very dubious to try and replace it but after a while i thought with the screen being new the adhesive might not be as strong, i heated the bottom of the screen and very very gently started to lift the screen with an opening tool, i was fortunate that when i eased it up the screen came away from the midframe as the adhesive in the centre of the screen had hardly stuck it and it was being held mainly by the adhesive round the edges and top and bottom,i replaced flex cable and all is fine now,i bought 10 broken screens and midframes of ebay to see if i could salvage any and make a complete unit, after heating screens and trying to remove them i smashed all 10 screens trying to remove from midframes,all the lcds broke right next to the bottom corners where the glass digitiser and screen are all bonded,
sorry for the long winded post, but hope this helps someone else.