Yes, there are comic cafes all over the place in Japan. Because of recession, homeless people stay there overnight instead of using a hotel. During day time, it is a quiet and nice place for internet.
iPad is a good idea for internet beginners. Your mother will be happy to have it. And you will get internet access there!
Fireworks in DC was excellent this year and I am sure next year should also be nice. Next year I will be working in DC a week after independence day.... So maybe I will be in LA on Jul 4th 2011??? Will see.