valuation of material stock

Hi MM Experts,

I am ABAP Developer I am new to SAP MM , i am confused about material price concept. i read some blogs and i understood that there are different organizational levels.

1. In that where the material is valuated ?? company level or plant level ??

2. If both are right , in which cases they prefer company/plant ??? please explain me with small example.

3. And how can we identify the material price is valuated at company or plant ??

4. If the material is valuated at company level or plant, is that is the final price to the customer(irrespective of their shipping address)??

5. how many types of prices are there for material ??

6. Is there any standard BAPI, which shows all prices of material??

7. And is there any standard BAPI which gives over all material stock (plant wise,storage Loc wise) ?

Regards

Venkatesh