Regarding to your first query who is going to contribute amount for subscribing shares???If its Company it will come under subsidiary company concept under Section 4(1(B))of the companies Act,1956. If the Directors are contributing then it will come under Section 4(1(c)) of the Act.Just decide before filing the person who is going to contribute.
Regarding to your 2 nd query there should not be any necessity for the Directors to hold shares.In AOA of the company there is no clause for Share Qualification,The situation does not arise.
With regard to your third query there is no need to mention anywhere as subsidiary company..until the subsidiary company can attach their accounts with holding company
I hope your query gets solved.If you need any further info,do let me know