Sorry for all the questions but it’s my first iPhone

Computational device’s are made to be used so I wouldn’t worry about it. There really isn’t such a thing as excessive usage. My iPhone’s are typically on 24/7/365 for every one I’ve owned since it is my only telephone (same with iPads, my Macs). iPhones like other computers have low power sleep states and built in systems to minimize power drain and heat when idle and are designed with the idea they’ll be on and available all the time.

I don't see how it could. Dropping the phone will damage it, but not general usage.