Let me try to answer you in an orderly fashion here...I may have missed your post in the craziness of the holidays - we are only home for 2 weeks, trying to fit everything in, before we head back to our winter place.
NEBS: I replace my neb cups every 2-3 months, usually have 2 in rotation. I have learned here to replace the tubing at the same time. (I usually only neb once a day now.) Here is the one I am using now - I buy 5 at a a time:
https://justnebulizers.com/collections/nebulizer-sets/products/truneb-reusable-sidestream-nebulizer
DISINFECTING: I have a round silicon trivet that fits in the bottom of the saucepan to protect the parts from getting too hot.
ASTHMA/BRONCHIECTASIS: I have both, although the asthma causes me more day-to-day issues with my breathing.
FIGURING IT OUT: Throat clearing & mucus are always an issue. Mine is minimized by: keeping allergies controlled (will not share a recommendation - everyone is different in this respect) and using guaifenesin generic (Mucinex) 600mg long-acting tablets and NAC 600mg(?) twice a day. I currently use the NOW Brand of NAC and have found it reliable. For Guaifenesin or Mucinex, be sure to get it without a decongestant or any other ingredients.
DAILY ROUTINE/VITAMINS: I am a minimalist - I take a calcium/magnesium/zinc supplement. If I am "up North" in the winter, I take a low dose of Vitamin D. I take an Omega-3 supplement to try to protect my heart - long family history. I take Vitamin C & Zinc if I am fighting a respiratory "bug." That's it! No other stuff - my vitamin and mineral levels are tested every couple years by my primary, and are all normal. With a daily multi-vitamin, several were way too high, including 2 B vitamins, so I stopped - haven't noticed any difference. I am vaccinated against everything possible - crucial to me because of my next point.
CONTINUE DOING: Isolation is brutal for me. This holiday season I made it through 2 airports & a flight (masked) two family outings, 3 restaurant meals, church, a little off-peak shopping and numerous family/friend gatherings and so far am healthy. Three years ago, I never thought that could happen again! I do have to say my family - immediate and extended, have always been meticulous about staying home when ill, and notifying others if they get sick right after a gathering. Our close friends are the same way.

I appreciate your thanks. My writing is my way of giving back to this group, who helped me immeasurably when I was diagnosed over 5 years ago, and as I endured treatment for both MAC and Pseudomonas.
Sue