Register absences for work center (Manufacturing 2009 R2)

Hi All,

I want to which method to use record absences for work center. we have few methods,

1. Registered Absences (Capacities--> Absences)

2. Reg.Abs(For work center) (Capacities--> Absences)

3.Absence (Work center --> Planing -->Absences)

Q1: If i want to record identified future absence after planing process over (ex: urgent maintenance, labor absence ) , What is the most suitable function for that ?

Q2: After record absence all planned , released orders will reschedule ? is it correct ? Even if we re plan the order will it (absence) be effect to released orders  ?