How do I remux selected audio tracks and subtitles using ffmpeg?

so I have a video (could be MKV or MP4) with multiple audio tracks and multiple subtitles (different languages).

What I want is to remux into a new video and:

1. selecting just 1 or 2 audio tracks
2. selecting just 1 or 2 subtitle tracks
3. making 1 audio track and 1 subtitle track (if available) as default so they are automatically selected when the video is played using VLC.

I've searched the net but caot find what I'm looking for. I've also looked at the "man ffmpeg". I think I may have to use the -map parameter but the examples given seems to be limited to copying just the audio.

Thanks a lot! :)