1. 
String reverse(String s){
	String result = "";
		
	for( int i = s.length()-1; i >= 0; i-- ){
		result += s.charAt(i);
	}
		
	return result;
}

2.
a.  Strings are immutable!  That means none of the string methods modify the String; they all return a new String object.

If you're curious why Java made this decision, here's a decent summary of some of the benefits:
http://java.dzone.com/articles/why-string-immutable-java

b. 

String name(String first, String last, boolean firstNameFirst){
  if( firstNameFirst ){
    return first.toUpperCase() + " " + last.toUpperCase();
  }else{
    return last.toUpperCase() + ", " + first.toUpperCase();
  }
}