grounding a poor conductor?

Yes, but slowly. When you touch some point on the object to ground, the electrons will move across the gap locally and discharge that little part of the object. That is, it will now have the same number of positive and negative charges in that region. But there will still be a voltage differernce between that grounded portion of the object and the rest of the object. Because the object is a poor conductor, only a small current (flow of electrons) will happen due to this voltage difference. But over time, this flow of electrons will eventually discharge the entire object.

NO, grounding one point of a large piece poor conductor ( or called insulator ) cannot remove charge fast enough, unless ground the total area in one shoot.Using reverse charge is the best way. Like positive ion charge can be neutralize with negative charge instantly.

yes it will. That's the meaning of grounding. But the discharge rate will be as slow as the poorest of the conductor.

Also are other ways to discharge a charged object as to confront it with equal but negative charged other.