Hello there,
3.0 seems to be working fine. About the two new buttons, one produces the rlf after you accept the settings and the other produces the lrf stright away. There is no need to press both. I had some fun duplicating files.
On the other hand, I tried (knew it wouldn't work, but had to) to convert a pdf straight from a web page. Didn't work and Calibre has crashed. I have reinstalled it and it won't go.
I don't know if it has crashed because there is a bug on the new version of Calibre, or Bookit, or because I tried to produce a few lrf files at the same time.
I'll try to fix it and tell you how it goes.
Nevertheless, this plugin is a must.