Hello, and welcome to Mayo Connect, where we are happy to walk this path with you.
First, I would like to point out that Connect is a community of people with similar conditions sharing their experiences and trying to help one another live well in spite of our health conditions. But each of us is unique, with different health and lung status and other conditions, so very much NOT "one size fits all."
Second, we are not medical professionals, and do NOT suggest you should substitute any of our suggestions for the directions given by your health care team.
Third, COPD is a fairly common disease, but bronchiectasis is uncommon (maybe 1-3 million people) , and MAC infection is rare (under 1/2 million people per year.) Many doctors have limited experience treating us, and may not be totally aware of the latest and best recommendations from the "gold standard" facilities like National Jewish Health, Mayo, Cleveland Clinic, and a few others. So you may read new things here that you would like to bring to your doctor's attention.

To answer your questions - Spiriva and its sister Symbicort are used by people here, depending on their other conditions.
Levalbuterol or Spiriva or Symbicort should be used before you neb with saline. It opens the airways and allows better penetration. I use Symbicort because I also have chronic asthma. My friend used Symbicort because he had COPD.
Most PEP devices, AirPhysio, Aerobika, Acapella - will help. The choice is individual - discuss with your doctor or ask for a visit with a respiratory therapist to see which is most helpful to you. I prefre the Aerobika, but keep a Acapella in my car in case I need help bringing up mucus when out and about.
Other here can chime in with their preferences.
Are you comfortable calling your doc with questions?
Sue