I humbly suggest the standard blade width of 8". The "power" gained by a wider face is at the cost of shoulder strain and efficiency of use- better to paddle with a narrower blade at a slightly higher cadence. Standard method for determining shaft length is to sit in chair and measure from chair seat to nose, add blade length to get total. People tend to buy paddles that are too long. I'm roughly 6' with a long torso and use a 51.5" paddle.

In choosing between straight and bent- bents are ideal if you paddle seated. If you kneel a straight shaft is more optimal. I have two ZRE paddles and believe they are the best dollar for dollar gear I've purchased. My main paddle is the equivalent of a ZRE-light, ten years old and used heavily over the course of that time (live near Ely and take frequent day trips and multiple Q trips every year). I bought the second (same paddle but at 52") out of mercy for my tripping partners (usually my brothers or cousin all of which are around 6'3"). Go for the lightest paddle you can get, don't crank on rocks, tie into the canoe at night and they will last better than a high quality wood paddle. The feedback they deliver when you paddle is amazing- ZRE has made my technique much better because it is so obvious when your stroke is inefficient (usually too long of a pull).