Summary:

Raising the hands in dua:This is proven from the Sunnah and there is nothing forbidden or contradictory in the Shariah to it.

Abu Musa Ashari (RA) narrated that the Prophet (Sallaho Alaihe Wassallam) made a dua, and I saw him raise his hands, until I could see the whitness of his armpits. (Bukhari)

Wiping the hands on the face after Dua:This is proven from the Sunnah and there is nothing forbidden or contradictory in the Shariah to it except for scholars say that it shouldn't be done inside of Salah (or in Qunut within Salah).

Musaa Muhammad ibn Al-Muthannaa and Ibraahim ibn Ya'qub and more than one stating that Hammaad ibn 'Eesaa Al-Juhani narrated to us from Hanthalah ibn Abi Sufyaan Al-Jumahiy from Saalim ibn Abdullah from his father (Abdullah ibn Umar) from Umar ibn Al-Khattab (radhiya Allahu 'Anhu) who said that Rasulullah (sallallahu 'alayhi wa sallam) when raising his hands in du'aa, would not put them down until he had wiped his face with them. (Tirmidhi)

Collective dua of the Imam and Muqtadi (follower) after Salah: There is no evidence in the Sunnah for it and since it is disruptive to late-comers of Salah (who are trying to complete their Salah) & in our times people have started considering it compulsory and a part of Salah; it should be be avoided. Mufti Ibraheem Desai (DB) advises:

The ulama should first educate their congregation on the sunnah method of Adhkar after salah and gradually inform them that the congregational dua is not compulsory and was not practised at the time of Rasulullah (Sallaho Alaihe Wassallam).Get the congregation to first understand that congregational dua is mubah and not compulsory. Do not condemn the practice without educating the congregation. This will lead to fitna.

Article in Full here:

www.central-mosque.com/fiqh/collectivedua.htm