1) G Bilkul sahi suna
Holy Quran 13:7
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وَيَقُولُ الَّذِينَ كَفَرُوا لَوْلَا أُنزِلَ عَلَيْهِ آيَةٌ مِّن رَّبِّهِ ۗ إِنَّمَا أَنتَ مُنذِرٌ ۖ وَلِكُلِّ قَوْمٍ هَادٍ
And those who disbelieved say, "Why has a sign not been sent down to him from his Lord?" You are only a warner, and for every people is a guide.
Holy Quran 67:8
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تَكَادُ تَمَيَّزُ مِنَ الْغَيْظِ ۖ كُلَّمَا أُلْقِيَ فِيهَا فَوْجٌ سَأَلَهُمْ خَزَنَتُهَا أَلَمْ يَأْتِكُمْ نَذِيرٌ
It almost bursts with rage. Every time a company is thrown into it, its keepers ask them, "Did there not come to you a warner?"
Holy Quran 67:9
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قَالُوا بَلَىٰ قَدْ جَاءَنَا نَذِيرٌ فَكَذَّبْنَا وَقُلْنَا مَا نَزَّلَ اللَّهُ مِن شَيْءٍ إِنْ أَنتُمْ إِلَّا فِي ضَلَالٍ كَبِيرٍ
They will say," Yes, a warner had come to us, but we denied and said, 'Allah has not sent down anything. You are not but in great error.'"
Imam Jafar Sadiq as ne farmaya
لو لا الحجة لساخت الارض باهلها
Imam jafar sadiq as ne farmaye zameen hujjat e Khuda se khali ho jaye tu ahle zameen ko nigal jaye
2) Yes Nabi and Imam only who were appointed by Allah