I live in Germany but want to manage my budget in US Dollars
You can override the currency Bludget uses from the settings screen.
What export formats are there
Bludget can export a report for printing, or a tab delimited file to import into a spreadsheet.
I want to delete a category
You can disable a category from the settings screen. You cannot delete a category as it may have expenses booked against it.
How can I delete an expense entry?
Just swipe an entry in the transactions screen to delete it.