Topic should be "Charted! - Easy/Normal etc."  I accidentally submitted it by pressing enter...

When it says beat the game on X difficulty can I skip around in the chapters and as long as I beat them all on X difficulty will I get the trophy? 
 
(Also, since when does GB let you submit a blank topic?)

Awesome.

Im not really sure, Every difficulty I played including crushing I played straight through the game...I would assume you could though, I don't see why it would prevent you from doing so.

i assume you could but i didnt risk it.

Playing through on hard.....for hard it's pretty easy.

i belive u can after u complete a chapter it changes from saying Completed on normal to completed on hard so if you do that for every chapter you should get trophy for completing game on hard

Yes, as long as every chapter is completed on a certain difficulty, you will get the trophy for the difficulty.  However, beating the final chapter is the last thing that needs to be done to get the award, even if you already beat it on the desired difficulty.