Application and Enrolment Copies

Do all the documents have to be sent as certified/attested copies?

No, not for application. You can send normal hard copies with the application documents. But please be aware that once you have been sent an offer letter by the admission commission, you have to send certified/attested copies of your language certificate, your University Entry Qualification (high school, etc), and your BSc certificate to prove the authenticity of those documents. You usually get 14 days after receiving the offer letter to send the matriculation form with the certified copies, so you should have them already prepared.