I think it depends on whether you intend to download books away from your internet connection. Generally most people would use their home internet to download books and then take their kindle away with them. All the 3G does is allow you to have a remote internet connection away from your home allowing you to download books whilst travelling on a train or bus or in a car.
You need to connect to your ISP for the connection. ISP in simple terms is Internet Service Provider.
It really is determined by your internet connection, it can take up to 20 mins to an hour
You can delete the internet connection settings in the Nintendo 3DS System Settings.
Slow internet connection or you need to clean out Temporary internet files and Cookies.
It depends on your internet connection speed.
it depends on the speed of your and their internet connection
The cost include phone connection cost, phone rent and internet rent. It is much cheap better to take a broadband connection if available.
It honestly depends on the memory that your Xbox has and your internet connection. 6.86gb will download faster on an Xbox that has 250gb and great internet connection, than an Xbox with 20gb and poor internet connection.
It depends on your internet connection. The better Internet package you have, the faster the loading.
It will depend on your internet connection... Normal internet connections will take about 80 min @500 kb/s (0.5MB/s)
It depends solidly on the internet connection you are using while downloading. The estimated download time using DSL is about 30 minutes. It has been known to take a lot less than that with faster internet connection.