This mod is called Beta 1 for a reason. Not all the features that it will have will be implemented. The bank is a future feature.
You are talking about an exchange rate. That is being planned. You can see that in the cash settings, it just isn't up yet totally because the bank isn't finished yet.
PhpBB2 Cash mod by Xore is a completely different mod. You can't compare Apples and Oranges.
If you have a feature you would like, Post it on Handyman's Tracker at http://trac.assembla.com/Handyman/report/3
Donating is possible from one user to another. On viewtopic look at a users avatar. Below Total posts should be an amt of cash and also the words donate. Click on that and you can donate to another user.
To do it via phpmyadmin is a little tricker. First backup your DATABASE!
Then You need to know the user_id of the user you want to donate to.
Click on the Database and then search. Put in the username of the person you want to use. Then search.
Scroll down the results and look for the phpbb_user table results. Click browse on that and it will open that table. You can get the user_id that way.
Now that you have the user_id, go back to the tables on the left hand side. Look for the table phpbb_cash_amt. Click on it. Now at the tables on the right hand side click browse.
You will see a list of user_id's , cash_id's and cash_amts.
On the user_id amt that you see, click on the pencil to edit it.
It will bring up a new screen. You will see a box. Look for the Value on the column and cash_amt on the row.
In that value you can adjust the cash there for that user. After you put in the new amt, then look for the Go box and click on that. It will go then to a confirm screen of sorts that shows affected row and query.