Multiple Questions with capabilities of the engine for my project (Open-GL, C++ scripts, Plugins/API, etc)

Hi everybody…I checked the forum and answerhub but I couldn’t find good answers for my initial questions.
I’m starting to focus on a new project that deals with many things and I need to know if UE4 could be the right choice for me.
What I need is basically a reply to these 4 questions:

  1. I need to work Open-GL based so is UE ready in this direction?
  2. How’s the situation with C++ scripts?
  3. Are there already features/plugins/API that could take a video frame and put it as a background to the game?
  4. Is there an easy way to access the framebuffer to capure the rendered frame and work on it with NVENC??
  5. What’s the best Nvidia board I could use for UE4 that has a GPU Direct?
    Thanks for any reply and have a nice weekend!