I believe you might still have to open a blocked account. I have yet to hear of a case where the German embassy has accepted a letter signed by a company as a proof of financial means.
You will need a proper health insurance once you arrive in Germany. You don't need to obtain it prior to your visa application.
The health insurance is usually paid on a monthly basis. For students, you register and provide your account details to your health insurance company once you arrive in Germany. They then withdraw a specified amount of money from your bank account every month.