The UPUSA is decidedly Protestant but is deeply involved in ecumenism and doesn't regard itself as the 'one, true church'. In Canada, of example, most Presbyterian churches merged with the Methodists and Congregationalists way back in 1925 to form the United Church of Canada. Presbyterianism and the wider Reformed tradition have produced many outstanding theologians, such as Reinhold Niebuhr, Karl Barth, etc. They tend to have a more creedal tradition than, say, Methodists or Baptists.
Presbyterian ministers have considerable freedom as far as liturgy is concerned. Worship services may be quite traditional or quite experimental - both even in the same local church. Preaching scholarly sermons is not unusual. Most Presbyterian ministers are very well educated, with at least four years of college and three years of seminary, often with doctorates.
In short, Presbyterianism has been part of the frabric of America since colonial days. Most people of Scottish ancestry were/or Presbyterian. Many Presbyterians, like most other mainstream Protestants, will shift from denomination to denomination, depending upon where they live and various other factors. In New England, for example, there are few Presbyterian churches because of an comity agreement made 300 or so years ago with the Congregationalists, the largest Protestant group in New England. Cross over into New York State and Congregationalist churches are few, Presbyterian churches are numerous. Both have Calvinist origins.
Quite a number of presidents have been Presbyterians. Wilson and Eisenhower come to mind immediately, but there were several more who served in earlier years.