Good for you...these enemas will get easier as you go along.
You raise good and important questions about caring for your enema equipment....keeping it clean and sanitary...as well as protecting the materials.
Soaking the nozzle in a Purex solution...and rinsing, rinsing, rinsing. That's helpful..Be sure you do not store the bag away until it's dry...moisture in the bottom of the bag can be problematic. I hang mine upside down for a whole day. My large bag has a mouth that can allow me to towel it dry inside.
You will doubtless get other good information from our forum members.
Right now....I'm headed upstairs for a lovely, relaxed enema series.