1) Does Islam or Christianity believe that all other faiths including Hindus are "True" as theirs ?
2) Do they accept that there can be another Awataar of God who takes form time to time ?
In Christianity Jesus was a one time phenomena. Islam does not believe that God ever comes in human form, so No.
3) Do they accept that one can live life on this planet by following their own way, instead of following the books viz Quran or Bible ?
No they don't. If they believed that then there would not have been a need for converting others.
4) Do Hindus also have right to find place in Heaven after their death ? (similar to what they claim for their own clan?)
Rejceting Allah is the worst possible crime and idolatory or deity worship as Hindus call it is an abomination. Catholics themselves worship icons although they claim not to do so. However it is okay to worship icons as long as they are in conformity with the Catholic faith. Protestants are against deity worship just like the Muslims.
5) Can Muslims say that Jews, Christians, Hindus etc (non-Muslims) are not Kaafirs ?
No Muslims can't say that and nor can Christians say that non-christians are no heathens nor can Jews claim the same status for Gentiles as that awared to a Jew.
6) Can Christians say that Jews, Muslims, Hindus etc (non-Christians) are not Infidels/pagans ?
Refer Answer number (5)