change the post display in category

My requirement is to change the order in hich the posts are displayed in a category from latest post first (default) to oldest post first.

Another requirement is to have a hierarchial display of the post but under the parent category, it should display the post only of its own and not of its childs.
For example, I have a parent category car and a chikld category maruti. I have 1 post belonging to category maruti and 1 post belonging to category car.

Now, when I click on car category link, it shows me both the posts (1 of its own and the other one of its child category maruti). I want that only its own post to be displayed and not its child posts and still maintain the hierarchical structure.