I have only done a couple of the paths (modules?) and find that my pets are doing better on their survivability. Up until now I have had to work hard to keep my pets up (usually I do dual bear or bear/devourer to try ranged).
In Fractals of the Mist I had very little problem keeping my pets up and fighting. I have not tried the older dungeons since the expansion.
The first few levels are (combat wise) easier than story mode dungeons. You might not be taking much damage because of that. It could be possible that at higher difficulty levels we'll be faced with explorable or stronger equivilant mobs and we'll have more of a challenge.
Yes. I am finding that pets tend to last longer or maybe it's because I am doing more pet swapping now. If I find my pets are dying too quickly I swap my current set for bears as they tend to have more life/toughness.