Hello and welcome to the forum,
Re the fuel gauges problem - First check to see if your fuel pump select switch is a double pole change-over (6 contacts) or a single pole version (3 contacts). If it is a double - one set of three should be free to use.
Now take the the signal/feed wire from each tank sender and disconnect from the two guages, reconnecting to the unused outside terminals either side of the switch instead. The unused center connection on the switch can then be used to feed the remaining fuel guage with the required sender signal.
This will enable the guage to indicate how much fuel is in the tank that is actively being pumped from.
Hope that makes sense - if not let me know and I'll mail you a diagram.
IMPORTANT! - Please do be sure that you are happy modifying your wiring before attempting the modification. Whilst relatively straight forward, believe me, <font color="red">electrical fires are not fun! </font> /ubbthreads/images/graemlins/blush.gif