They swab test you and the tests are rushed through, so you get the results quickly. Well that's what happens where my Mum works. Though this has normally been for people who had something else, so that's why they were at the doctors, and the swine flu happened to be picked up. They see whether its H1N1 or another strain. The H (haemagglutinin) and the N (neuraminidase) are just two proteins on the outside of the flu that are classified by a number based on their type. It is these two proteins that are used to identify the strain (probably the antigens that we produce antibodies against).
I think the diagnosis over the phone, is because they are trying to limit the spread and if you are an otherwise healthy person taking tamiflu and staying away from other is the best treatment (doesn't really matter if you have what is known as regular flu). They don't need to waste time testing you, its quicker and easier to just give you the drugs based on your symptoms. Obviously this is for normally healthy people who would usually fightoff flu on their own anyway.
There is nothing to say swine flu is more dangerous, it's spread around the world has just been noticed as it killed a lot of people in Mexico. Without those deaths, it may have just passed everyone by, as people who get really ill with it have some underlying health issue e.g. immunocompromised, have respiratory issues, just like 'regular' flu. The only thing is it is an animal flu and therefore relatively unknown with regards spread, treatment etc.
http://www.ncbi.nlm.nih.gov/pubmed/ scientific article database, there'll be loads on flu.
Enjoy