Eh? How do you come to the conclusion is saves money? The saving of a couple of sets of tyres would be vastly outweighed by the damage to wings and bodywork, and the need to increase the allocation of engines and gearboxes to support it.
Putting everyone in reverse order is not going to generate a clean race. You just have to look at any reverse grid series to see that.
Plus, its still going to be difficult to overtake. Your not going to see someone come from last to 1st in 15 laps at Monaco.
Reverse grids are a stupid idea in any formula where there isn't either car parity or a wealth of overtaking. Plus they also need to be cheap formulas in terms of damage repair.
The 3 session qualifying works fine. People should park it and put their attention on the things that need fixing.