2maemo.it, you are using it wrong. It is not for making random queries and it is not to replace telephone module gap.
It is for making the same query many times. You have it on your desktop, it updates every 2 hours (configurable) and shows your balance. You don't need to launch phone and enter code if you want to know balance. Just look at desktop.
1) Yes. Or use ussdquery.py or ussdPad
2) No. Only if you want to change it.
3) No. It is a widget. All widgets behave like this.