congregational dua

Q: Is it permissible to make dua in congregation after fardh salaah? Is there any hadith in which it has been called an innovation in Islam? 

Q: I would like to know the ruling concerning dua after the congregation in the masjid. Should it be done audibly or should it be done inaudibly. Some people take offence at the fact that in certain masjids the day after congregation is made inaudible and they feel that because it is a congregation we should make the dua are similarly for everybody in an audible voice.

Q: I am the imam occasionally in my madressa. After the fardh salah of zuhr. Would it be correct if I raise my hands and make dua softly to myself so that no one in the congregation can hear or is it correct to make a loud dua to which the congregation says ameen?

Q: When a person is reciting masnoon duas loudly wherupon others say "amin" (for example the imam after salah, at the time of nikah, etc), should he change the pronouns in the duas to plural form? For example, should he say "rabbi zidnA 'ilma" since he is making dua for the whole congregation? What would be the plural form of the dua "Rabb-irhamhuma kama rabbayaani sagheera"?

Q: After the fard prayer, some imams make dua in congregation while some do not. Some people say it is bida to raise the hands after fard prayer in congregation. But according to a hadith I read, after fard prayer, it is one of the best time to make dua. So, according to Sunnah, what should be done after fard prayer?

Q: Is it permissible to make loud congregational dua after a programme (eg. Zikr, Bayaan, etc.)?