Gosu, when you say "In a way reaching level 90 super fast puts you ahead of other pet collectors" do you mean you want to be ahead of other pet collectors in pet numbers or in speed of getting to 90? I can't think of an easy way to do both at once. For pet numbers I'd probably pick up engineering and pay attention to it, do as much questing as possible in zones with zone drop pets and map out the quests with pet rewards. And do the Darkmoon Faire! Good xp AND lots of pets!
I like leveling as a tank, so my dks usually level blood. Killing individual mobs is marginally slower, but you can aoe pull and I love tanking dungeons. Do each dungeon once as it opens up to get the quests, that's good xp. Too many dungeons fatigue me though, which slows me down, so I have to bounce back and forth, quests, dungeons. I try to wowhead up the quests with the best rewards and make it a point to do them.
I'm not sure about the trinkets. Probably just whatever you have on hand. Trinkets aren't that huge a deal while leveling.
Swiftwind, as fast as leveling is now, it's really really hard to keep up with mining as you go, so I'm not sure that's the best analogy.
There's absolutely nothing wrong with taking your time leveling to 90, picking away at your proffs, questing, dungeoning and raising your pets. In fact, I'll probably take this route with the toon I have on the Warcraft Pets Guild's server. But I've leveled a lot of toons, at this point I'm more interested in ambling around and picking up on subtleties I've missed than racing to the end.
There are also advantages to grinding pet levels at 90 too. Being able to fly everywhere would be super useful. Also, you're going to have to be able to fight off the mobs around the pets you want to capture, and all the Pandaria zones have unique pets to capture. I fully intend to take advantage of my high level toons for Pandaria-zone captures as soon as possible!
None of which is probably useful ... oh well. Sorry for the ramble!