Can't answer number one
number two really does come down to personal preference and riding style. How do you split your mileage between highway and streets? A higher proportion of highway mileage might suggest a higher front sprocket for you. Are you an aggressive rider? If not, again a higher front sprocket might be more in order for you.
I have one of Brent's new rear sprockets, anodized black. For me, it really was the best option, as far as tooth count, color-coding, price, and speed of receipt. OE sprockets are expensive for what you're getting (IMHO), and they may not exactly be the fastest option. Sprocket Specialists take forever, I'll never buy from them again, I had Brent's sprocket in about 4 days, and it looks awesome.
If you have a motorcycle jack, switching out the rear sprocket is not that hard, and you can do it by yourself.
