2 hacks for DLE (categories and news publishing window) how to implement?

Question

DLE

Good afternoon, I am writing one project on cms DLE, it is necessary to make the following functionality:
- the ability to cause the publication of the news not in a separate window, but on the main page in the popup (the design of the popup does not really interest me)
- when adding a new news, only the main categories shone in the list of categories , and when you click on the main category, the categories of the parent's children would open. (preferably in the form of 2 selects)
- select script
1. we light 2 selects, the 2nd select is not active by default
2. 1 select contains only parents. 2nd select only children
3. select the parent in the 1st select, unlock the 2nd select and it contains the category of children of this parent.
Could you tell me how it is possible to implement this or can someone come across such an implementation?