uploading asset accounts and foreign currency valuation

hi sap guru's

1) i have small doubt in asset uploading,

what is the difference of uploading asset accounts year starting and year middle , what is prerequisites to upload assets

what is the transaction code for upload fi-asset accounting point of

(not lsmw /bdc)

2) in foreign currency valuation T-CODE f-05

there is two options 1 is open items 2nd is balances pls

clarify what is the difference between those open item and balances

thanks for all sap guru's in advance