How are you using your battery? Are you running on battery power when AC is available? Run on battery whenever you need to and plug it in whenever you can. You can plug or unplug any time you need to, regardless of the charged percentage, and you never need to completely drain your battery. Just make sure you don't run on AC power exclusively, as your battery needs to be used regularly to stay healthy. This should answer most, if not all, of your battery/charging questions:
There's no need to do that twice a day. If you're at the desk, leave it plugged in. Running on battery for a few hours two or three times a week is fine.
You shouldn't leave it plugged in all the time, as the battery needs to be used regularly to stay healthy. But that doesn't mean you have to run on battery all the time, either. As I said before, run on battery whenever you need to and plug it in whenever you can. If you're putting a cycle or two on it every week, that's plenty. I really encourage you to read the Battery FAQ. It explains everything.
