Like what exercises will help me improve tone quality, sustainability, reach high notes with ease (without changing my 7c mouthpiece) and play at any volume without having an airy/puny/weak sound to it. Also, is it normal for a trumpet player to lose lip strength? When I play for a period of time, my lips start to get "weak" and I can't play notes really well anymore, it sounds really airy or no sound is made at all, only air.

Due to the vibration of your lips when playing, it's perfectly normal for your lips to go numb while practicing. To work on your tone, try singing the notes. If you can sing them well, you can play them well. Try to do breathing exercises to increase your lung capacity and power. Take a breath that is so deep that it hurts, and hold it in for 30 seconds, then slowly release it. Do this five times before each practice.