No, I don't think the case at hand says anything about that. What happened here is that the Copyright Office was asked specifically about DVD/BluRay ripping, and said "no". But that's all they said. The case of music ripping has some precendent, but not here.

Obviously an unprotected file has no "means to effectively control access", so copying it should be legal under the DMCA (it's the circumvention that's illegal, not the copying per se). But m4a files are usually DRM'd, so my guess would be that unless a separate determination is made it's still not kosher.

I don't know that there's been a court decision covering that specific case, so it might still be in a legal gray area. To me the decision in the Betamax case suggests that it would be legal. Others say the precedent doesn't apply because the Betamax case was looking at time-shifting, and space-shifting is different.

However, in any case avi to mpeg4 is not equivalent to DVD ripping from a legal standpoint. Because of the DMCA, US law makes a distinction between media that is encrypted for copyright protection purposes and media that is not encrypted. So since DVDs are CSS encrypted and AVIs aren't, the two are covered by somewhat different sets of law.

No, copying a file from one device to another is illegal (space shifting) not changing the format (media shifting).