Disabling compression is at the server level rather than code level (and it's a real easy config change too). However I can see that being an unfavourable solution for some of the busier sites.
Adding a few random bytes to a response seems to be an easy fix and doesn't require compression being disabled.
Adding a random amount of random bytes will not defeat the attack, it would only slightly increase the amount of time required by making the side channel noisier.
Adding a fixed amount of random bytes will have no benefit at all.
Not following your assertion. Suppose the reported size was always a random epsilon larger than the actual size. Choose epsilon so that its small enough to benefit from compression and large enough to obscure the BREACH. Why doesn't that work?
The mitigation suggestions are all at the application level which will make fixes less likely as SSL/TLS is usually considered a security silver bullet.