Ok I looked a various users at differ rep levels and they seem to be in order. Could you PM with more detailed info (usernames) to whom your referring to so I can check .
What you give in frubals is the amount of the frubals you have divided by 250. I'm not sure what the formula is for negative frubals but it is quite a bit less.
Coins are earned by your posting activity. You get $5.00 for a new thread, $1.00 for a post, and some coins for reading a thread. The banks pays 2% interest per day (compounded) on the amount deposited in the bank.