yer the render is kinda choppy.... and yer, wasnt a good idea to resize it.... but if u are going to, hold shift when you do it so it maintains the proportions
lol never ever ever ever ever ever ever magic wand i personally use pen tool it takes forever sometimes but on a render that size it should take no time at all. just go slow with your renders and be a little more picky and they'll turn out great :] nice attempt but i suggest using a way bigger stock next time and use another method of cutting than the magic wand.