Some points I'd like to mention with regards to the matter:
Adam Lanza made an entire spreadsheet (I think it was in excel format) listing all the spree killings he could find information on, with details such as the amount of deaths, wounded etc. So he was not just collecting information, he was doing it in a thorough, in-depth manner. A manner that even other people interested in the events would consider rather obsessive.
We know Adam Lanza used the moniker "Smiggles" (on the old Columbine forums) and by all evidence also "fuckcomments" (on Youtube). Both Smiggles and fuckcomments commented on the spree killings of the past, often mentioning specific "technical issues" such as the choice of weapons etc.
This is information he got from the media. I'd make a case that because the information about the previous shooters were so detailed and available through the media, Adam was able to compare them (he had an analytical mind, that needs to be said). Then on that basis he would choose the weapons and target he believed to be best suited to cause the most deaths. The information available to him might have made his attack more deadly and more efficient than it would have been otherwise.
Then we have a point that is harder to prove - Previous spree killings may have been seen by Adam as a template for resolving his own problems. Adam was extremely isolated from society, suffered delusions and by all evidence was very unhappy with his life. Perhaps if he didn't have the example of previous shooters, he would have likely just committ suicide.
_________________
Life is like a tram - you need to know when to get off.
"Bullet Time" - a school shooting film from Poland