Good morning, No this is not a problem at all. I have been using the toothbrush for over a year and remove the brush head every time after use. The metal piece is very sturdy.

You mean with a payment slip? Yes, simply select "prepayment" when ordering. The bank details will then always be sent to you by e-mail.

According to the manufacturer, all brushes can be used with all Oral-B handpieces. Except for the Oral-B Pulsonic series. So it should fit. Kind regards.