Yes the area is small but there is a full screen button at the bottom-right corner of the game-screen. This should make the game much more pleasing to play.
The rotation of the ship is based on where your mouse is compared to the center of the ship. This means that closer your mouse is, faster you can turn in less mouse movement.
In my testing period I haven't encountered any problem with the ship getting stuck in the corner but I can only guess it is because of the small screen not showing the entire area. So I think that playing in full screen is the way to go.
I'm not near the computer this week so I won't be able to fix the speed as well.I personally liked it as it was the minimum speed required to dodge the bullets of the enemy ship when touching it( the ship turns slow so enemy ship takes long to turn big angles )
Thanks for the feedback-it means a lot!! I can only blame it on myself as the CSS and HTML coding could have been better but I left it at the default code which unity compiled for me.