begin again, mary's song, haunted (Acoustic), blank space, and fearless are all classics

I consider a song to be "classic" if it's remembered and referenced 20, 30, 40 years after its debut. It's difficult to assess if she has any because she's only been around for 10 years.

If I were to guess what could be potential classics, I'd say YBWM, SIO, and BS.

Yes, all of her songs.

Yeah no

Love Story
You Belong With Me
I Knew You Were Trouble
Shake It Off
Blank Space
All You Had To Do Was Stay

Let's check iTunes (ignoring 1989 songs):

666 Taylor Swift I Knew You Were Trouble
771 Taylor Swift Love Story
781 Taylor Swift You Belong With Me
902 Taylor Swift 22
1163 Taylor Swift We Are Never Ever Getting Back Together
1375 Taylor Swift Mean
1479 Taylor Swift Our Song

I beg you pardon, Love Story was a globla smash !

No, especially not outside the US.