Can PTSD be mild? Do the traumas have to be of a certain kind?
In order for something to be diagnosed as a disorder by a mental health professional, the client typically experiences distress and impairment in activities of daily functioning. 

If the time frame is under 3 to 6 months, please consider "Acute Stress Disorder" as a possibility. I agree that the DSM V is going to be a useful resource for diagnostics.

Trauma, in any form, does pose very specific challenges for diagnostics and a treatment plan. For further reading on trauma therapy, I highly suggest "Life After Trauma: A Workbook for Healing" by Rosenbloom and Williams (2010). Treatment will be dependent on the practitioner's training, and the formulated diagnosis. You are welcome to research efficacies of therapeutic interventions.

Therapy is very useful for any and all of the items you have mentioned. If you are attempting to get insurance coverage, usually a diagnosis from a qualified professional will qualify you for therapy (at least here in the United States). A good diagnosis could take a few sessions to formulate. It's sometimes a longer process if someone suspects trauma.