Please indicate how Opera is more free or better than the web browsers already included in Debian.
I did not specify Opera as an example. Opera does perform much better on older hardware than Iceweasel.
You are also free to properly package it yourself and find a sponsor to upload it for you (assuming you are not already a Debian Developer yourself, which I am guessing you are not).
I do not see the need to do anything other than sign the package and drop it into the repository, as it is already completely functional for Debian. I understand this is not the Debian way and I understand that in quite a few instances many packages created for Debian by outside parties could still have problems. I am reasonably certain that this is not an issue with Opera, given the widespread use and the fantastic job they have always done packaging their browser for Linux.