replying more specifically, as others have said you will need to add =if( statements to help choose option.
Another useful function is =INDIRECT() inside () can be a text string that looks like an address, eg Sheet1!A1 or Sheet2!A1..B3 for a range, or a cell in the spreadsheet where you've assembled a text reference that looks like the examples. This enables you to select via calculation which sheet is wanted and which cell.
Other functions that I use heavily for the type of work you want to do include: MATCH INDEX OFFSET
I tend to avoid VLOOKUP/HLOOKUP. These will return a result even if its not an exact match. You can find yourself picking up the wrong information. I use MATCH, with a zero for the MATCH_TYPE so that I get the exact match or an error, not a near enough match. You then need to use the MATCH result in an OFFSET function to fetch the value. MATCH tells you how far along the match was found. OFFSET is then given this number to index into the array. You have to subtract 1 from the match result used in OFFSET.
Use the build in help. It is a great learning aid. Check help for the functions you're familiar with and look around under the "See Also" link at other possible functions.
