3. What kind of latency can I expect ?

For wider coverage, and to avoid tracking, geostationary satellites are "parked" in a fixed position relative to Earth, at 22,300 miles above the equator.

Radio waves travel at the speed of light, or about 186,000 miles per second. So any traffic from you to the satellite has to go 22,300 miles up, through the satellite, and be retransmitted 22,300 miles back down to its destination.

The net effect is that this one-way communication adds about a minimum of 240ms to the round trip time. This is from an ideal position as close to the satellite as possible (probably in the ocean at the equator). And remember, that if you send for a web page both the request and the response have to travel these distances in addition to any ground distance, for a minimum roundtrip of 89,200 miles (480ms). Add to that the terrestrial internet latency, gateways, proxies etc...

A more realistic expectation is a response of about 500-1000ms for two-way satellite, and 400-500ms for one-way.

Software and protocols can reduce the effect of latency for certain applications, but they can't change the physics, the latency remains.

Note that newer LEO (Low Earth Orbit) satellite systems, like Space-X Starlink are in much lower orbit, and produce sub-50ms latencies that are directly comparable to ground/undersea networks. Those LEO systems achieve that by orbiting at much lower ~500km altitudes, at distances similar to any ground internet service. The low orbit poses challenges, as much larger constellations of thousands of moving satellites are needed for coverage.