Anyone good with Illustrator?

[Joe 90]

Alright guys, I finally got round to trying my hand at vector images. Thankfully using Live Trace it was simple.

Theres just a few parts of the image that aren't 'perfect' and I don't yet know how to add to the paths accurately to make them look better.

this is what i've got at the moment;



you see the top goes flat because of the original image being crap and i don't know how to improve that :/ theres also a big toward the bottom left of the helmet where the black line of the shield shape gets a bit thick on the inside

I've not yet got to grips with resizing the artboard (or if its even possible) and how to get rid of the white background so I've got a transparent png :/

if anyone can help me out make it a bit better i'd much appreciate it whilst i carry on watching these training videos!!
http://www.shuwarriors.net/images/Warriors-2.ai


*also, is there a way to get the text to alight 'top' as it were so that it is basically aligned to the arc of the top of the image (much like in my sig)