if your account goes under that amount withing the time when your visa is being under considearation, it might not work out. I have always did my best to keep the money in just to simply avoid any crazy problems.
I have done drive through recently and it was really good. Gave my passport and filled form. The whole process was done in less than 5 minutes. They are open but be aware that there is a lunch break when they close. After that I think they open again at 13:30.