There is a way to see how much money each member has donated so far by checking the member list. Take note that if someone leaves the gang, even for a short period of time, this statistic will dissolve.
In terms of management, everyone of rank 95 and above, can manage this cash.
Now, there are positive and some negative issues when using the Gang Treasury.
The positive are:
1.It allows you to store money without risking them being lost to another gang by stealing them from you.
2.It allows the administrators to send out money to members in need of them. (Payments received are not mobster taxed).
3.Money in Gang account increases the ranking of the gang.
4.In the future you will be able to build things for your gang (like special wonders which will give special attributes to the gang members).
The negative are:
1.Everyday, 1% of the total amount stored is lost (you know, many scums are around ready to put their filthy hands on your stash, and they get away with it).
2.Whenever you send out a payment, 5% of the total money sent is lost (you need to pay those whom transfer it heh ?).
3.You cannot make more than one payment to each member per day and the amount of that payment can never be greater of the 10% of the total stored amount.
So it's up to each gang leadership to decide how to utilize this feature.