Thanks!
Let me make sure I have this straight:
1 - More gangs can give more selectivity.
Yes, more front end selectivity, but does not determine selectivity of the IF stages where the number and type of IF filters determine the selectivity. RF selectivity helps with front end overload type problems and IF selectivity determines how well it handles adjacent channel interferance.
2 - More gangs in itsself will not really influence the sensitivity, but may indicate that other parts of the tuner are higher end?