Yes, that is correct.
Yes, you would either need to add a new page and type in the quote, to copy/paste a cue and change the text that way.
That's correct, you are not able to delete a specific verse from the Bible Cue that was inserted. I will pass this along to see if we can change that to allow it.
No, you cannot add your own themes at this time. We are working on adding Templates (similar to themes). When those are added, you can create your own Templates.