My question is, is it saved in the 'cloud' together with my Bitdefender account, or I will lose all saved WWW passwords and login after I reinstall Bitdefender?
All credentials are synced to your central account. You can restore the wallet account after a reinstall or fresh install as long as you use the same central account.
Just make sure to check in the "last sync" time to not lose any credentials you just added.
Thank you so much for including a photo. I didn't know this page exists there.