Woo, finally figuring this forum out!
I think I'm challenged, lol.
Now for the critique; I see what you mean by your hand. Bad habits like that suck, had a few in my time. The way I like to envision it is I'm holding two ice cream cones in my hand and they can't fall. It really helps to get your thumb on top, at least for me!
As for your elbows, pull them back next to your sides. I still myself have this problem, and my instructor always tells me to literally grip my sides with my elbows until I get used to the feeling. No, it isn't the greatest habit, but once I finally work out my problem I won't be allowed to grip anymore, huh?
Also bring your hands down a bit, but that'll be easily fixed once you bring your elbows back!
I love your seat, wish I had one like that!
Overall, good work!