This should be done for its own sake and not to confer wealth, fame or other benefit to the living. Within reasonable limitations, some improvement is possible. Common sense can work wonders. While it is certainly possible that prayer could change the course of rivers and the lay of mountains I have not personally seen it done. It is, however, of demonstrated benefit in changing men.
Blood sacrifices are to be condemned as barbaric and cash sacrifices usually benefit only one party.
Not in the classic sense. Feng Shui can open the mind and train the eye, giving rise to a sense of balance, harmony and order. This can be reflected in the placement of objects in interiors, or in a general awareness of space and circulation. A beautiful, well-maintained fish tank pleases the eye and has an interesting quality if you like that sort of thing. It is not a cure-all for Feng Shui problems.