AARGH, half of the post is gone
ill summerize the other part:
Whatever currency we use, there still is number formatting. But this is also regional. In the US they format a number like 12,345.7 while in Belgium they format it as 12.345,7. Also the sign is often on a different place.
We can use the same locale to answer that, to give each player the formatting he is used to.
Regarding credits:
the short form of credit is "c". I propose to change this to "cr" for "c" means also "cents", in this case as in "credit cents", thus 1/100 of a credit.