My boxing days are 1/2 of my lifetime ago, so take my comments with a grain of salt.
First of all, looks good, nice sweet science happening there. Seems like you have some pop.
I notice, though that when you return from your jab, you're dropping your left hand. I remember that much from my coaches. Later in the series, you're holding that left hand down by your belt, maybe that was because you were working your right hand and it was part of you were working on, but my dated experience reminds me that keeping those hands up throughout those exchanges is really important, especially following a jab, when you are likely to face a counter.
Incorrect. This is called the "Philly Shell" or the "Crab Defense" by the Mayweather camp. The lead hand is supposed to stay low, although he has it in a wrong position.