The correct answers to these open questions are the following.
What do you think should be the ROLE of the free press (consider all types) in a democratic country?
The role of the free press should always be to report the truth and nothing but the truth, which means never bias information or confound or distort public opinion.
In what ways might today's media in the USA seem to fulfill such a role or purpose, and in what ways might we argue the media to be failing to fulfill its role.
Not always. The major news companies in America serve particular and economic purposes of their owners. For instance, Disney owns ABC and ESPN; among other news channels. So many times they serve the business interests of the owners and are not completely objective in covering the news.
What should we expect from it?
The truth, and nothing but the truth.
What should we demand?
The same, and to never bias the reality in favor of one side or the other.
How does the media inform us, and how does it shape our attitudes and beliefs?
The media shape our attitudes and beliefs because people trust the media, thinking they are telling the truth and serving our interests, but that is not true, as I explained above.
Consider the media coverage of the 2016 candidates during the primaries. Consider Trump's attacks on the media (general or specific). Any threats or dangers for our democracy?
Yes, the media received constant critics and attacks during the Republican presidential campaign, but as I wrote above, the media is not a "white dove," it has served the economic and political interests of political groups and big corporations in the past and in the present.