Linking 50 files

I need to create a master spreadsheet that will have fifty separate worksheets attached to it. I want to create a validation list on top of each row with the 50 spreadsheet names and once selected, the linked formula in each column will recognise the selected validation list name and link to that file (the cell references will remain unchanged, just the destination file will change). I hope this makes sense and can anybody help.

Also how do I make the Save As dialog box appear with the File Name the same as a selected cell.

Thanks