Answer to Question 1
The due process clause does not require a preliminary judicial inquiry into the reliability of an eyewitness identification when the identification was not procured under unnecessarily suggestive circumstances arranged by law enforcement.
The Fifth Amendment's self-incrimination clause has also been invoked with regard to identification procedures. In particular, some defendants have argued that being forced to participate in a lineup or photographic array is itself incriminating and, as such, violates the Fifth Amendment. However, in United States v. Wade, 388 U.S. 218 (1967), the Court held that the privilege against self-incrimination does not limit the use of identification procedures. The Court's rationale was that even though incriminating information can result from identification procedures, such evidence is physical or real as opposed to testimonial.
Answer to Question 2
Generally speaking, a confession obtained in violation of Miranda or some constitutional provision will be excluded. However, just because a confession is obtained illegally does not mean that any subsequently obtained evidence will automatically be excluded. In fact, illegally obtained statements are themselves considered admissible in certain instances. There are essentially three lines of cases involving confessions and the exclusionary rule: (1) cases involving the standing of a party to challenge a confession, (2) cases where the prosecution seek to use a confession for impeachment, and (3) cases where a defendant seeks to exclude evidence that is fruit of the poisonous tree.