url redirection/domain registration

I just registered my site, ionlyshoot4money.com with godaddy. i am using it with my wordpress.com blog. this is a three part question:

1. my site only works as http://ionlyshoot4money.com and not http://www.ionlyshoot4money.com, how do i rectify so both work? and preferably if someone types in the www i want it to automatically make it change to read http://ionlyshoot4money.com

2. i just realized that registering a domain through wordpress is only $15. so since i registered through godaddy ($10) and had to buy credit on wordpress ($10) to register the domain, is there any way i can get this $5 back?

3. also can the ionlyshoot4money.wordpress.com automatically change to read http://ionlyshoot4money.com?

i appreciate the help!