The wealth system is obviously not going to be perfect. It does not adequatly reflect buying very expensive items. The D20 Modern Wealth system nicely removes that minor book keeping. However, it suffers a bit with reference to large items, but the core mechanic is sound.
Now, I would suggest that Monetary rewards work like the Profession check vs Wealth increase for going up a level. Roll a few dice (Not nececarily d20's), and throw in a modifier, and increase the wealth score accordingly. Let each player roll that increase for them selves. For results that fall FAR below the characters wealth score, dont increase the wealth at all.
Example:
The players recover a breifcase full of cash. Lets assign it a value of 5d4 'WEALTH'. Let the players divide it themselves.
- They could give them selves one die each.
- They could roll and divide by number of players
- They could give it to one player.
- They could set it aside as party funds (a party wealth score).
At 1d4 each, they will probably each get a +1 wealth increase. Dividing it by number of players will probably end up doing the same.
If they give it to one player who has a Wealth of 10, and they roll 15 on the dice, the players wealth score could go from 10 to 12 (+1 for rolling higher then 10, and +1 for the 5 points that 15 exceeds ten by).
If they set up a party treasury, then the treasury would have a 15 vs Wealth zero for a final total of 4 (+1 for beating zero, +3 for 15/3).
As for charcters sharing wealth, you could use a similar mechanic to the profession check mechanic. If you have a wealth of 18 and your friend has wealth 7, you could do the following. 18 is greater then 7, and 18 -7 is 11. That means you boost your friend to 10, and lower your self to 15 (18-3 for 3 point increase to friends wealth). Or you can use any arbitrary math formula you find satisfying.
END COMMUNICATION