Upload edited video to YouTube
I'm not familiar with facebook video, and maybe someone else can help with that. 70MB is insanely small for 30 mins of video. What are the properties of the source video (in Premiere, right click the source video, select Properties). Copy/Paste that info, and add it to your question if you can.

Leave the frame size / frame rate the same as the original - Premiere has a "Match Source" button in the output settings, just ensure it is ticked. Often scaling down the resolution lowers the quality too much, and I find you usually get a better trade off keeping the resolution and lowering the bit rate instead. What is the bitrate in the preset? For video files that need to be transferred, I usually output using H.264 codec, at 6Mbps target rate. That still gives me almost 50MB/minute (with audio), but retains the quality level where I need it. You could likely push that bitrate lower - try lower bitrates, see what your video looks like (if this is a fixed camera / fix background video, likely you can push the bitrate pretty hard without much impact to quality). But you won't get the FB file size with that codec, so that extra info would be handy.

For uploading, do you have Google Drive? You could sign up a free account there, and sync the files, which might make putting the video to YouTube easier than uploading direct: https://support.google.com/youtube/thread/5937118?hl=en