Answer: You must read Fatihah and a short suurah. Instead of a short suurah, 3 aayas or a long aayah also qualifies, such as Aayatul-Kursiy, but not "alif laam miim". The minimum length of what must be read in addition to Fatihah is Al Mudaththir, Aayas 21-23:
{ثم نظر ثم عبس وبسر ثم أدبر واستكبر}
Question: Can we cut those in 2 (read first part in 1st rakaat en the 2nd in 2th rakaat)?
Answer: If they each part reaches the required lenght above, yes. But this is pushing the limits, and in one saying of Abu Hanifa one must read a complete aayah of the minimum length in each rak^ah (part of an aayah is not enough).
Question: And what is the smallest amount to read in Qiraat? Will the ayah ''Ya Seen'' fulfill?
Answer: The minimum length of what must be read in addition to Fatihah is Al Mudaththir, Aayas 21-23:
{ثم نظر ثم عبس وبسر ثم أدبر واستكبر}
If you read only an aayah, or part of one, it must be equivalent to this in length.
