Is it permissible to sacrifice imported livestock (Such as Romanian, Australian, etc.)?
Praise be to Allah, and peace and blessings be upon our master, the Messenger of Allah.
As long as the sheep meets the prescribed Sharia age and is free from disqualifying defects, it is valid for sacrifice regardless of its country of origin. Therefore, it is permissible to offer sacrifices from various sources, such as: Romanian, Australian, Spanish, Indian, Sudanese, local (Baladi) livestock, and others. And Allah the Almighty knows best.
Is it permissible for the young woman to turn the suitor down if she had no feelings for him?
Yes, it is permissible for her to do so.
What is the ruling on preparing food for someone who is not fasting in Ramadan?
It is forbidden to prepare food for someone who is breaking their fast without a valid excuse in Ramadan.
Doing so would be assisting in sin, and assisting in sin is itself a sin.
Allah says {what means}: "but help ye not one another in sin and rancour" [Al-Mai`dah/2]
Is it permissible to combine Zuhr and Asr prayers for being occupied with a wedding ceremony?
No, it isn`t permissible to combine Zuhr and Asr, or Maghrib and Isha because of being busy with a wedding since the exemption for combining prayers is based on lawful excuses, and this isn`t one of them. And Allah Knows Best.