As long as it lets the entire animation be shown, you can use whatever you want. A good rule of thumb is to use your stream's base resolution.
If they're larger than your canvas, make it fit the scene. In OBS Studio you can right click on the browser source > Transform > Fit to screen. Don't use any resizing method that breaks the aspect ratio by stretching it.
If you think the latest updates to your animations are not being applied or no alerts are showing at all, refresh the browser source. In OBS Studio you can right click on it > Properties and you'll find the button at the bottom. Otherwise, delete the browser source and add it again. Hide/show doesn't refresh a browser source.
If it still doesn't work, reach out to us on Twitter (@getStreamChamp) or Discord (johnRivs#6347).
It'll depend on the threshold (highest takes priority). If multiple alerts end up matching, one is picked at random from the ones you have enabled.
No. They'll still use your Streamlabs page. All events your alerts respond to happen normally and nobody's flow gets altered.
Yes but it's not advised—you'll lose sharpness. If you're going to, don't use any resizing method that breaks the aspect ratio by stretching it.
Yes. Just make sure your alerts still look good. Some animations come in from the borders and if you don't align it with the borders of the scene, it'll look like it's coming from thin air.
The minimum amount for an alert to be shown. For example, in the case of donations it'd be US dollars and for resubs it'd be months.
It's not taken into consideration when using test buttons.