Need to help to build a web portal

I need to develop a web portal where users can upload their videos and images. This portal needs to have two user modes (admin and user) where in once a video is uploaded by a user it has to appear in the "new videos" web page of the portal quite automatically without the admin having to handle it every time.

I'm quite a newbie in web development and I need help from the basic level. So apart from the above mentioned I'm also looking for some help in the following lines: 1) What framework/combination should i choose ?(angular/mongo/JS or wordpress or SQL/php). Basically the ideal combination for backend, frontend and DB. 2) What are the measures needed to maintain scalability or future expansion. 3) Should I host my own videos or use VIMEO or google storage(YouTube) ?4

Thanks for any help in advance! I'm really looking forward for some help.