THX for the tip. You're absolutely right. 8) The easy mode can be completed ramboing yourself through the levels and for the normal mode you already need a little cover. But hard requires cover and a little tactics which I definitely will try tomorrow.
I had major trouble getting the last trophy for crushing, but I finally did it, and can offer some hints about the really hard ones.
1) In that very hard battle in the cistern, you don't have to drop down at all. Just backtrack outside to the Jeep, and when you return they will all be running around down there. No sweat.
2) For the final battle outside the sanctuary, get the bad guy's attention, then run back down the corridor the way you came. Take out the ones that followed you and and carfully pick the rest of them out from safety.
3) Check out this video for the plane crash in ch 4.