I have stainless steel pans in the bottoms of my cages & I put about 1 1/2 - 2 inches of shavings in them.
I do also. The stainless steel is more expensive up front, but less expensive in the long run.
The adventage of shaving pine is the soft floor for chins. But Is it gonne be the cause of bacteria/Bad Smell or Fungus?
There should not be a problem if you clean it weekly. Make sure your bedding does NOT have cedar in it or any "odor controllers". Pine bedding is the best, I think. Some use a bedding made from recycled paper. That is good also.
About the small wire I really do think If I use them for a long time it's gonna be the cause of painful paw?
The wire, if cleaned weekly, should not be a problem IF you put a couple of pieces of pine wood for them to stand on. Wire floors, if they are not kept clean OR if the chins have nothing else to stand on, can cause bumblefoot. Bumblefoot is an infection/inflammation of the feet of a chinchilla. It is very painful for the chin and can even be dangerous, due to the infection it can set up. Bumblefoot is apparent if the feet are swollen, warm to the touch, dark pink or red from inflammation, and in extreme cases the skin can split and the feet will bleed. This would need a vet's exam and treatment a.s.a.p.
Jo Ann