Reaching Pudong Airport by 12.45pm, is it possible for us to take 14.15 shuttle bus to Suzhou?

Yes, you can take the bus at 14:15.
But the bus doesn’t stop near metro line 4, as I know, it stops near metro line 1, and you can take it to Leqiao to transfer to line 4.

To Tongli, you can go to North Bus Station or North Square Bus Station, from where you can take a direct bus there.