ummm...I'm not very familiar with the socks protocol, but in theory the http one should be faster because socks is working like an extra layer in the network stack and so should slow down the transfer a little....but I don't think it's that much. maybe you can test the same download with both options and let us know then...
I downloaded the tor extension and its auto configured but now firefox says the proxy is refusing conections when its enabled its configured exactly how to tutorial says to configure it also any reason why.