"Party of One" is brilliant, I agree it's one of the best Pinkie episodes.
It's been ages since I last saw season 1, but my favorite was "A Dog and Pony Show", the episode that made me a Rarity fan. It's one of my favorites in the whole series.
There are other MLP sites I visit sometimes, especially Derpibooru for images. But this is the only MLP community where I have an account and actually post anything.
I can't say I've heard anywhere near all of her songs, but from the last few albums, "Protagonist Syndrome" is my favorite. Deserved a lot more attention!