1. In the given situation, you may ask your mother not to sign any paper, especially the so called consent letter without seeing the contents of the Will and confirming her benefits made in the Will.
If you apprehend your maternal uncle to play any fraud on this, you may better file a suit for partition asking your mother's legitimate share out of her deceased father's property. Let she not whisper anything about the Will or even the knowledge of an existing Will in her suit for partition.
She can also seek an interim injunction restraining them from alienating or encumbering the property in any manner till the disposal of of the main suit.
2. Your mother can very well make a Will for the properties to which she is commanding clear and marketable title.
.No probate is necessary for Christian and Muslim Wills.
3. No t necessary, because it is a civil matter, instead you may better file a suit for partition.
4. Yes, you are entitled to inherit your mother's share along with yor father, if living.
5. The administrator of the Will alone has the rights to administer the proeprty bequeathed in the Will, hence your uncle's intervention in this regard would be considered as contrary to law/rule.
6. You can take action as suggested in the first answer above.