Depends on the guy. Some guys looks are all that matter. Veeerry few guys looks don't matter at all. Most guys looks matter, but aren't everything. I think the majority of guys will fall into the 4-7 category on how much looks matter.
Well that is highly dependent on a guy and the standards he has. For a man who has high standards will have at least 7 or may be even 8 out of 10 and that may be because he himself would be 8 out of 10, so if a man is very handsome, attractive then most probably he will have high standards as far looks are concerned, so the woman being physically attractive to him is also important, he would then expect the woman to be at least 7 out of 10, because he gives importance to looks.
However some other guy may not give so much importance to looks, he would not have much reservations on looks, so even if a woman is 3-4 out of 10 he would still be okay with it.
The way she looks means a lot because it's what brings you to her. From the start it plays crucial role so it's like a 10. Then it's a completely different story because if her character is not desired you are more likely to got dissapointed and the 10 becomes 1.. :P
I don't know, I really wouldn't rate a girl on appearance. I've seen some amazing transformations. I'd say I need to connect with this person. If my bond with her is like Bonnie and Clyde. Hell, who cares how she looks?