Hello!

1. For Jot Server it is enough node js, npm and forever plugin for node js (VPS is enough). Also your server should allow to open at least one secure port for external connections. It will be used to connect Jots Server with your site.

2. If you mean your own Jitsi meet server, which is used for online conferences, then it also requires node js and web server and during Jitsi meet installation the all required software will be installed automatically VPS also may be enough for it for the first time.

It is hard to tell exactly which server do you need to stand video streaming, it depends on number online members and some of features which can used parallel with video conferences like video recording or streaming to another server like youtube and etc..