1. The grounds for appeal are limited in federal court? No more limited than other courts
2. Guilty verdicts are high because people take pleas? That is not why and doesnt make a lot of sense. A guilty verdict means there is no plea. Pleas are not considered guilty verdicts. Plus, if guilty verdicts were high because of pleas, that would mean that the feds wouldnt negotiate because if it were reversed, then it was the defendants not negotiating, which would mean they feel comfortable about their case, leading you to believe a guilty verdict is less likely.
In reality, feds conviction rates are high because the feds do proactive investigations. They build cases with wire taps, confidential informants, grand jury subpoenas, etc. This results in a strong case to present to the jury.
On the other hand, state cases are more reactive investigations. Someone gets killed and the cops try to find out who done it.
3. Convictions typically arent overturned often but it happens for a lot of reasons. That said, trial judges are given a ton of discretion as to what evidence comes in so as long as the judge followed the right analysis to come to conclusion, evidentiary reasons typically arent why a case is tossed out. Federal judges are typically the smartest of the smart so its not likely they messed some evidentiary standard up but certaintly possible.
4. Agree i could see some of the other defendants plea out