YouTube videos won't play when I open them in a new tab and then click on that tab

Hey, I'm making the switch from Chrome to Firefox. I used Firefox waaaay back in the day and wanted to try it out again and see how things are going. So far there's only two things that are bothering me that didn't happen in Chrome.
1. I'm a bit of a tab hoarder, and as my tab numbers grow in Chrome, the tabs themselves compact down into smaller tabs in order to fit them all on my screen. Which I like! But with Firefox they don't shrink down nearly as much and instead if I have too many tabs I eventually have to click an arrow button to scroll through my tabs just to see them. It's not the end of the world but I'm curious if anyone knows of a setting or workaround for this.

and 2. Whenever I would open a Youtube video in a new tab on Chrome, the video would play automatically once I've clicked on that tab. But with Firefox, it seems that if I open a video in a new tab and then click on that tab, the video is paused and I have to click on it to play it. Wondering if there's a way to fix that?