Can I use this plugin and Lightview Plus (other any other plugin with similar function) at the same time?
No! (doesn't make sense)
Possible to use this plugin with other plugins (like referrer detector) using the JQuery-Library?
Yes, Floatbox doesn't depend on external JavaScript-Libraries and therefor it is compatible to referrer detector
and other plugins using JQuery.
Is it possible to change the options of floatbox.js without editing the file itself?
Yes and no, actually only some options (theme selection + animation options) can be adjusted at the plugin options page.
How do i embed a video from vimeo (youtube)?
Just follow the instructions of this
howto.