Do you have to clear your snorkel at the end of mask and snorkel recovery when you surface?
Yes, you need to clear your snorkel and sound off with your lips wrapped around the snorkel without breaking the seal.
With harassment, dirty breaths, water down your throat through your nose any advice on how to avoid getting an infection in your lungs?
The only thing you can do to avoid infection is to take care of your body by sleeping, eating properly, and maybe supplement vitamin c to boost your immunity. Technique wise I always recommend placing the tip of your tongue on the roof of your mouth to act as a kind of splashguard when you are breathing through the snorkel on buddy breathing. This will reduce the amount of water you might aspirate while breathing through the snorkel.
I’m having issues with buddy breathing and getting water out of the snorkel and staying calm, how should I practice this? Also I have an issue with staying calm with goggles off.
I would practice by just floating in the water with a mask on and pretending to pass the snorkel to your buddy by taking it out of your mouth and putting it back in. Then practice by doing it with your mask off as well.