Laravel FFMpeg Getting Started Questions

[Mr-Anonymous]

I apologise for these questions but inspite of reading various topics and SO, I am still unsure on these.

1. Is it best to resize the videos during file uploads? If yes, what ideal size / dimension do I resize it to when my audience are Mobile, tablet and laptop / desktop users?

2. Do I need to add setKiloBitrate() during file conversion or is it okay if its not set? if yes, what is a recommended bitrate when converting videos to mp4 and webm that will be played in HTML5 video player for mobiles and laptops?

3. Users will be uploading their videos that will be played in Videogular HTML5 player. So, is converting the file to mp4 is enough? Or should I consider converting the videos to both mp4 and webm for most browser's compatibility? At the moment, I am planning to convert to mp4 and webm and wondering if converting to ogg will also be necessary.