Windows Machine for UE4 Game Development - Advice Needed.

Hi Folks,
I recently started learning C++ and UE4. My focus is to do game development right now but I am also interested in doing cross platform mobile apps development using Unreal which I heard is possible. I have two questions and I need advice from you guys on that:

  1. Is UE4 and C++ a good option to do cross platform mobile app development ? I am a developer with over 10 years of experience in doing web development in Ruby and recently Elixir but I know Java, Objective-C and Swift well so C++ is not a very different territory for me. I know I can use Xamarin and Unity for this but UE4 and C++ would also serve both purpose right ? I have heard C++ is more powerful for game development than C#.

  2. Secondly since my college days to writing this post I have always used Mac’s. The last time I used Windows was somewhere in 2007 so I do not have much idea about the windows machines. UE4 is not performing quiet well on my mac as it has only 4 GB of ram so I am looking to buy a windows machine. Can you guys recommend me some of the decent machines which I should buy to use UE4 to its full capability ?

Thanks and please let me know if you guys have any more questions to answer my post.