Hello, My Daughter Is 6yrs Old Has Dufficulty Breathing From

Hello,
my daughter is 6yrs old has dufficulty breathing from nose during sleep. she has this problem from last 2yrs. I took her to ENT last year and she said that her adenoids are 100% enlarge, and she has some fluid in her right ear too. She suggested us to take out her adenoids so i agreed for the surgery.
But i want to know if her immunity will be low, and she will be more prone to infection or not as adenoids fight infection for ent? What if they grow back after surgery or will her voice be changed after surgery or not? Will she able to sleep normally after surgery without snoring, and breathing through her nose? she suffers from cold almost whole winter , so after surgery what are the chance that she would not catch cold during winter?