In the case of federal warrants being issued or not issued - it is not 'evidence' that matters it is PROBABLE CAUSE that must convince the Federal Juege or Magistrate to issue one or not, the same as in local or state warrants.
A warrant is not required for an arrest. If the officer has ample evidence that a crime has been committed and circumstances of immediacy pertain, they can arrest someone on the spot.
Probably the FBI.
No. If the search warrant is invalid and they illegally searched you or someone you know (like without reasonable cause, or without the warrant) then they can't use any evidence against you. To the best of my knowledge, anyways. I don't know how many ways a search warrant can be wrong though...if they were searching for like, pot, but found cocaine, they CAN use that though. Or a gun, or something like that. If they have the warrant, they can use it. If they searched without the warrant, its invalid and inadmissible 100%.
no
Only if they have obtained a federal wiretap warrant from a federal judge.
only if there is evidence that support a probable cause against you.
Yes, the states have no authority to countermand or nullify a federal warrant.
If they were arrested as a result of a search warrant being executed - it all depends on what the search warrant was for (what crime/offense) and whether the evidence being searched for was found (I'm assuming it was).
If any evidence is acquired without a proper warrant for search and seizure, the evidence must be thrown out before court and the jury cannot use the evidence against the accused in a court case.
The officer(s) can 'contain' and guard the newly discovered evidence in place while they return to court to amend their warrant or apply for a new warrant based on the newly discovered evidence.
Fed is an abbreviation for federal, or national governance and its executive instruments. A federal warrant is an order for search, arrest and seizure issued by a federal court.
The 1987 Supreme Court case that supported the use of evidence obtained with a search warrant that was inaccurate in its specifics is Massachusetts v. Sheppard. In this case, the court ruled that as long as the police officers acted in good faith reliance on the warrant, the evidence could still be used against the defendant.