Is it permissible to omit wiping the ears in ablution (wudu') and suffice with inserting the finger into the ear canal? And is the ablution (wudu') and ritual bath (ghusl) valid if wiping the ears or rinsing the mouth (madmadah) and sniffing water into the nose (istinshaq) are intentionally omitted?

Wiping the ears is a Sunnah (definition) according to the majority of scholars. Rinsing the mouth (madmadah) and sniffing water into the nose (istinshaq) are Sunnah acts in wudu' and ghusl (definition) according to the Malikis and Shafi'is, and obligatory in both according to the Hanbalis. They are obligatory in ghusl but not wudu' according to the Hanafis. Washing the ears is obligatory in ghusl, and it suffices to pour water over the head with the strong presumption that water has reached them. It is advised to strive against obsessive whispers and to disregard them.