First of all, the Rosetta mission was a joint NASA-ESA mission, where NASA was in charge of providing the power supply. However, the US Congress pulled the funding on the mission and ESA had to do it alone. This was after most of the spacecraft was already designed.
Second, ESA never developed nuclear-powered spacecraft. Even though it is a policy choice due to the fears of blowing up nuclear material in the atmosphere, it is also reflection of a space agency created specifically for non-military purposes. While NASA is also a civilian agency, it has a strong connection with the US military and access to materials such as plutonium.
Third, different Nuclear Power sources in Space (NPS) have to be developed in order to guarantee the availability of the raw material. There is no point in developing a long-term programme based on rare or very hard to obtain nuclear materials.
First you need to mention where you are exactly. Internet service over satellite is usually sold through local providers. Furthermore, different satellites have different coverage areas.
Second, if you want high speed broadband, you will need a Ku/Ka band (small antennas) satellite terminal. The problem is that in South America, it is more common to use C band (big antennas) satellite terminals that are slower than Ku band since the spectral bandwidth is smaller and more expensive.
Third, the latency is basically the same for all Geostationary satellites and in practical terms is about 250ms from the transmission latency and 150ms for the latency of the entire transmission chain. As systems improve, this latency gets reduced but the transmission latency only depends on the relative position of the terminal to the satellite and the speed of light.
Forth, above 70C latitude it is not possible to provide Internet over satellite with geostationary orbit since there isn't enough visibility of the satellite on the horizon.
On a clear disk you can seek forever.