No, you cannot. You need to take the test once again to reach at least 7.0.

Find the suited language certificates on the website linked above

No, you need to submit your proof of English proficiency together with
the application, otherwise your application will be rejected.

No, you do not need to provide a language certificate (such as IELTS or TOEFL).

Your BSc certificate or the TOR need to make it explicit that your BSc program was in English! To avoid any problems in the application procedures, please upload the corresponding document (TOR or BSc certificate) as Proof of Language Document and clearly mark (highlight) where it says that the program was taught in English.

If you still have valid and sufficient proof of English language
proficiency, such as an IELTS score, you can use it again for the MCNB
application (even if 'officially' expired). Else, you can submit your
master’s degree certificate (i.e. diploma) as proof of English language
proficiency. Please upload the MSc certificate in the section where you have to upload the language certificate - make sure to highlight where it is said on the certificate that the languagte of instruction was English!

If you have not finished the English-taught master's degree,
you need additional proof of English proficiency on C1 level.

Find the suited language certificates on the website linked above