To be tired it is only in your mind.
Trust me when you love something you don't need motivation.
Yes it is better to keep training even if your muscle is still sore.
I love to be sore and when I feel sore I train even harder.
To be a good bodybuilder you must be a good observer.
Use what you have in your gym. Try to do my training program, you will lose your fat and gain muscles at the same time.