Show all posts and show related posts of specific company

Hi to all,

I have attached an image (Screenshot).

The first half shows the main page. How I will make all posts of all companies (plus the future ones added) to appear on the main page?

The second half shows the company NP PLANICK S.A. which is the result of the advanced search. Under the Website Categories there is a green box pointing an area of the page (I painted this area green just to show the part of the page where the posts will be shown).

How I will make all related posts to NP PLANICK S.A. (and only these) to appear on that green area of the page?

So the first question is how to show all posts in general on the main page and the second one is how to show the related posts of a company to that company’s page.

Thank you in advance.
Iason