After having submitted a personal valid E-Mail Address will anything change in regards to E-Mails sent from and received from that E-Mail Address?: 3

No, nothing will change in that context. Opolis will not replace your standard E-Mail application, such as Microsoft Outlook or Apple Mail, but provide a parallell and separate service for all your confidential E-Mails and attachments. So the entire mechanics in regards to your non-Opolis E-Mail account will be unchanged. You can use your standard E-Mail Address like you always did and no standard E-Mails will be automatically diverted to or sent from Opolis. - However, to send confidential messages absolutely secure you will log into and use Opolis. Opolis E-Mails do not leave the Opolis mail server system and are therefore - unlike ordinary E-Mails - entirely protected and can only be read by the Sender and the authorised Recipient and nobody else