1. apple's own Files actually does support SMB, not FTP though. You can try Documents app (support SMB, FTP, SFTP).

2. try VLC, or Outplayer (this based on mpv)

3. I just use web interface of the bittorrent client

4. I don't think there's any non-JB app that can match Android's wifi analyzer apps, there are something like this though https://apps.apple.com/us/app/network-analyzer/id562315041