We have sucessful developed a Video Platform, VOD(video on demand) and Live Video. We have a lot of experience in live transcoding and streaming video. Your solution supports many inputs type as camera, webcam, video capture card, RTMP, UDP, RTSP, RTP, HTTP...output is encoded in H264/AAC over RTMP, UDP, HTTP...target devices are PC, tablet, smartphone( iOS, Android, Windows phone), smarttv.
My transcoder is based FFmpeg. i have worked with FFmpeg for 4 years. I already done the same features as your requirements. My transcoder support a lot of input and output types: flv, mp4, mgp, webm, mkv, avi, mov...the transcoder also can automatic generate thumbnail and integrated logo and subtitle into video.
We can use FTP client(firezilla) to multiple uploading to your server. using FTP is very safe, it can resume uploading when lost connection.
Let me help you.