Questions about WordPress customizations

Hi, all

I’ve a few WordPress customization queries, and would appreciate any feedback from fellow users.

The envisaged end-product:

1 In addition to home, there will be three other (navigation) tabs at the top, representing three content categories.

2 When each author write a new post, the piece will be assigned (manually or automatically) to one of the categories. All posts under the same category will appear in chronological order when the associated tab is selected.

3 All posts by the same author will be listed in chronological order in his personal page.

Can the above objectives be achieved using plugins, eg, BuddyPress, bbPress, with little or no hacking?

Alternatively, if hacking is required, is it likely that the modifications will be broken in any future WordPress, theme, or plugin update?

Thanks in advance for any pointers or feedback.