My setup is a Yaesu FT-897D, Signalink Audio Interface, ARR SP432VDG RF switched preamp and 7 element UHF Arrow II Antenna.
I have noticed the same packets that you mentioned on question #1. They show up on the soundmodem but they are not decoded in the Greencube Client. I assume they are telemetry packets, malformed packets caused by signals clashing or packets not decoded even though they are loud and clear.
As for power, I can make it with the max 20W that my radio puts out. Considering I am using an antenna with less gain than the usual tracked array, 100W with a high gain antenna is overkill.
The satellite team is the one that switches the bird between 1200 or 300.
73 Fernando, KF7R