Unless you have advertised (or someone else) towards a domain/landingpage before, AdWords won't know anything about your site yet and therfor the LP wont give any immediate effect on your QS.
Your initial QS if you have a new account/domain will be based on the avg. QS from every other advertiser for that keyword. So if you get a bad QS blame every other advertiser
What happens next is that Google Bot (for AdWords) will come and visit your site, this can weight your QS up or down and will usually happen in a day or two. However this should and usually don't affect it much unless you have done something really bad on your page.
Never the less, QS is around 75% based on CTR. What most people miss though is that the CTR part does not show until you have a certain ammount of impressions. Next thing that most people don't know is that QS is based upon your exact match, meaning that if you have a broad matched keyword that is x and you got an impression for y x or x y then that does not count towards your QS. Make an experiemt if you don't bealive me, put a single keyword in broad, phrase, exact match in the same adgroup and see if you get a different score on them, which btw is a very stupid thing to do in the first place - stab at shitty agencies!
Also for the comment "need to have high pos to get high ctr to get high qs", ctr/QS is weighted based on position. This is why most non-newbie advertisers don't give a cr*p about positions for positions sake, they care about the highest ROI/ROAS, if that happens to be position 8 or position below domain x does not matter. This is also why newbie advertisers think that AdWords is expensive
