Demesne,
some things first:
You haven't taken your SAT's yet and the SAT score is an important factor. Assuming you will get above 1400 on SAT 1 and above 700 in each SAT 2, and considering your O and A level results though, I think you should apply to the top unis with a couple of backups.
Do you have preferences about which state you want to apply to, or is your only criterion the academic ranking of the university?
Are you asking for financial aid or do you plan to pay the full fee? B/c if you are asking for financial aid, then:
Are you a Pakistani or a US citizen/ Canadian citizen/ green card holder?
B/c if you are a Pakistani citizen asking for financial aid, then some unis don't give financial aid to international students, and you'll have to look at that factor as well. If you're paying full, then you can apply anywhere though.
The top unis are:
Stanford
Harvard
Yale
Columbia
Princeton
Dartmouth
University of Pennsylvania [UPenn]
Cornell
Brown
MIT
Duke
Northwestern
University of California, Berkeley
Harvard to Brown in the list above [those 8 unis are the Ivy League btw]
You can see college rankings on usnews.com
Some good backups (places whose merit standards aren's that high) for international students asking for financial aid, in my days, used to be:
Ohio Wesleyan
University of Southern California
Brandeis
If you're not asking for aid then your backups can be more highly ranked unis.
Also, check with your counselor about your college list and ask her to recommend places to you.
As for info/deadlines, ye tum khud kar sakti ho. Go to www.google.com, put the names of the unis in search, go the uni websites, browse into their admissions page.
most of them are just www.[name of uni].edu
Look up the admission deadlines, and once you know what they are for all the unis, go to www.sat.org and look up info about registering for SAT's and do for a date which is in time for sending SAT scores to colleges.
And you were asking abt online applications, I think a lot of them have online applications now.
Another thing you want to do is contact your english teacher in A levels, and two three more teachers, let them know you're applying abroad and will need recommendations from them.
Lemi know if you have questions. Good luck :-)