FI-MM integration - valuation class questions

Hello Experts,

I am new in SAP MM Field,I have following  doubts in FI-MM integration.Please make me clear,

1) Is one valuation class can assign with n number of transaction keys?

2) Is one G/L account can assign with n number of valuation class?

3) I created one material with material type ROH and assign it with valuation class 3000.When I uploaded the Qty by M.T 561 found the below result-

ITEM  P.K      ACCOUNT        ACCOUNT SHORT TEXT     ASSIGNMENT    TX   AMOUNT

1        89     380000                Inventory-Goods In                  00000                       100-----debit

2        91     410000                Oem products consume          20131124                  100-------credit

now,when I checked the transaction keys in table T030 I found that G/L account 380000 have BSX transaction keys and valuation class 30000,but for G/L account 410000 the transaction key is GBB and also valuation class is different.So with point 3 I have some doubts,

a) why for account 410000 valuation class and transaction keys is different?

Please help to clear my doubts,Thanks in advance.

Thanks & Regards,

saurabh awasthi