What is ruling on praying behind the Imam of who is not following of Rasoolullah's Sunnah such as,
1. Not tying the hands and leaving the hands and pray,
2. After (Surah Fatihah) Walallallin not saying Aameen,
3. Not raising finger in Thasahhud,
4. When Tasleem saying only one Salaam,
5. Immediately after the prayers start supplicate (Du'a).
Can we follow the Imam if there is no other imam available at the time of praying?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions. There is no harm to perform prayers following this Imam. Since the scholars are not unanimous concerning the ruling of the matters you enquired about. Therefore, it is not allowed to leave a congregational prayer for the above reasons. Indeed, performing prayers in congregation and developing love, affection and unity among Muslims are more important than the matters you are enquiring about. Allah knows best.