Salaah

Imaam leading the Salaah with his trousers below his ankles

Q: In the area that I've moved to, the imaam of the local Musjid leads the Salaahs with his trousers below his ankles. Does it diminish from the Musallis reward to follow such an imaam and is it permissible?

Also, after every Salaah, the imaam systematically makes the same short dua after reciting taqdeer once and istigfaar thrice, followed by Ayaatul Kursi, Tasbeeh-e-Fateemi, the fourth kalimaah thrice, and then the same lengthy dua after each Salaah. Is this allowed? And if not, Should I as a Musalli remain in the gathering so as not to create any conflicts with the locals, or rather just leave and perform my Sunnahs?

Digital prayer mats which count the number of rakaats

Q: What is your opinion on this:

http://homeshopping.pk/products/Digital-Prayer-Mat-in-Pakistan-.html

It shows the rakats prayed on near the place of the sajdah, so the one praying can see the number of rakats he has prayed. But according to hanafi fiqh reading and understanding such as from a piece of paper during salaah is makruh? I heard in a lecture that Aisha radiAllahu anha would switch her ring from finger to finger to keep the rakaats in record. And also the qawl of Ibrahim an Nakhai that there is no harm in doing so. True?

Folding one's hands after ruku when praying behind a imaam who reads longer zikr than ''Rabbana lakal hamd''

Q: Must a Hanafi fold his hands after ruku when he prays behind a imaam who does longer zikr than ''Rabbana lakal hamd'' such as;

رَبَّنا وَلَكَ الحَمْدُ حَمْداً كَثيراً طَيِّباً مُبارَكاً فيه

Rabbana wa laka l-h'amd, h'amdan kathiran tayyiban mubaarakan fih