Perhaps you could try and se if there’s any group consentrating on the Vulgata? I.m.o. that would be a very good place to start if one’s main goal with Latin is religious. Good thing about the Vulgata is that it is written to be easily understood close to how people spoke rather than Cicero’s overly elloquent speeches or Virgil’s poems full of archaisms.
Regardin words, I’m very sure that there be frequency lists for the Bible. There are for Hewbrew and for Koinê listing every word used in the Bible base dupon frequency. Ah, 30 minutes of Googeling and voila: http://www.dtc.umn.edu/%7Ereedsj/vfreq.txt