Hi Nadia,
You can get more info form FI team about exchange rates. Actually they are the one who maintain exchanges rates at source side.They will be helpful which fields we need to maintain and how rates can be loaded thru flat file.
While loading thru flat file, the info object which going to hold decimal values(Exchange Rate.factor from and factor to)may need to defined as decimals then only you may load data .other wise you can see numbers without decimals. Even in key figures in bw " -" "/" may not bw allowed. you may need to do manual divisions and place in flat file.
Thanks