Those are the million dollar questions!
Coincidentally, just before I saw your post, I was on my weekly "what can I learn today" dive into Google Scholar, where I found this amazing article:
https://pmc.ncbi.nlm.nih.gov/articles/PMC11211698/
I will summarize (briefly) but encourage each of you to read it for yourselves. Warning: This is not and easy read! But, it answers many of your questions and mine.

My takeaways
- With all of the tests available, ongoing studies and new treatments, more doctors that before are recognizing Bronchiectasis.
- Treatment protocols are rapidly changing, and new drugs and regimens emerging - but only those dedicated to treating Bronchiectasis, Pseudomonas and NTM are going to be able to keep up. So it is more important than ever to have your care directed by an expert.
- The number of links between BE and other conditions/diseases is better understood than ever (See figure 2.)
- Pseudomonas is increasingly demonstrated as predictor of poor outcomes with Bronchiectasis.
- Airway clearance, hypertonic and isotonic saline, pulmonary rehab and exercise are increasingly linked to successful outcomes.
Here is one quote: "... Notably, the results of the study emphasise that long-term airway clearance can ameliorate the clinical course of patients with bronchiectasis, beyond reducing daily symptoms and improving HRQoL.

Overall, studies have shown mixed results regarding which airway clearance technique is superior. This is likely due to the heterogeneity of bronchiectasis patients with regard to varying airway calibre, unique sputum properties and individual respiratory strength. From this perspective, the authors recommend that airway clearance management be tailored to the patient's needs, as the most effective airway clearance technique is one the patient will use consistently and successfully over time.

Airway clearance alone may be sufficient to manage patients’ symptoms and improve their quality of life, but many patients have ongoing symptoms or exacerbations despite effective airway clearance. In this situation, it is recommended to add additional symptomatic and/or preventative treatments in a stepwise manner until disease control is achieved..."

Finally, the "heterogeneous nature" of bronchiectasis is stressed - therapies truly need to be tailored each patient.

Happy reading all, I am going to try to download the entire text and run it through an AI tool to simplify, but this will be an experiment, and I am in my "entertainment week" at home - 3 more groups coming between now and Monday.