About a preposition which is followed by a clause.

I think rules concerned seem to have been established as follows.

<Rule 1> A Preposition is dropped when that-clause follows
<Rule 2> Prepositions can take a clause as its object except for that-clause.

Hence, as for me. (1)(2)(3)(4)(5)(7) is correct according to Rule 2
(10) is correct according to Rule 1
(9) is incorrect according to Rule 1.

(6),(8) is incorrect because (5),(7) is correct.

Can you correct me if I am wrong?

I have no idea about whether he will come soon. ----(1)
I have no idea about when he will come. ----(2)
I have no idea of whether he will come soon. ----(3)
I have no idea of when he will come. ----(4)

I am not sure of whether he will come soon. -----(5)
I am not sure whether he will come soon. -----(6)
I am not sure of when he will come. -----(7)
I am not sure when he will come. -----(8)
I am sure of that he will come soon. -----(9)
I am sure that he will come soon. -----(10)