I agree that the book has most of the background you need, but I definitely recommend watching the operas!
I finished watching them (the last one took 2 nights, since it was over 4 and half hours long). I enjoyed them very much and liked the music better than I thought. (I usually only like early and baroque music. Romantic music usually gives me a headache or puts me to sleep . . .) It's the Met, so I was more than halfway through before I realized what amazing singing was going on! They make it seem effortless even when singing for 4 hours straight!
Watching (with English subtitles) made much more sense to me than reading the libretto, too. There were a lot of emotional undercurrents (and questions of motivation) that I would have otherwise missed.
Now I have lots of questions about interpretations and themes. I'm leaning toward a totally feminist interpretation, but that's just me. After all, Brunhilde was predicted to be and turned out to be the world redeemer, not Siegfried. But then they all die in the end -- a very Aeon of Osiris, not to mention Victorian, version of redemption. (BTW, there does seem to be a lot of violence against women in the story, but it wasn't so graphic or pervasive to make it painful to watch . . .) I find I'm already differing with some of the interpretations of the tarot creator, but I don't think that will spoil the cards for me.
So for background,
here and
here are English translations of the libretto WITH the Rackham illustrations on Project Gutenberg.
And
here is a different English translation side by side with the German.
I watched the 2010-2012 opera productions on
https://www.metopera.org/Season/On-Demand/. (If you're really cheap like me, use the free 7 day trial.)
I haven't finished reading the tarot book yet or used the cards, but I'm going to do all that this weekend. I DO think all the learning is worth it, but, as usual, it just brought up more questions . . .