Meaning of Ulelamr

I was going through this answer on the shias imam and came across "ulelamr". This word is used in the verse 4:59 . According to the answer this is what ulelamr means > With the above observations, ulel 'Amr are identified with the appointed Imam(s). Imams can also be identified with their full knowledge of everything. They never say "I do not know" in response to any question. 2 questions: 1. What is the sunni point of view of the meaning of ulelamr? 2. What is the context of this ayat 4:59 ? (any account of what was happening during the period of revelation of this ayat) (Both sunni and shia stance)