...I love all the stories and pictures - truly hope I'm in one of them!
You will be!
...have upped my cardio significantly...
That is one-half of the battle preparation. I hiked with a gentleman who never hiked in his life. He was a mountain biker and was in very good shape. He made it up to the summit without a problem. Sometimes, our minds play tricks on us. Yeah, we may think we are in shape, but once we get on that trail we realize, "Well, maybe..."
...My biggest hurdles for this trip are altitude, weather and hydration/nutrition as I tend to loose my appetite when exerting myself...
Hydration and nutrition you have control over. I, too, lose my appetite, but I occasionally nibble on the candy bars. My "hurdle" is from Trail Crest to the summit. This is the first of three of the "I-hate-this-part-of-the-trail" (the second is the dipsy-doodle down to the JMT junction back up to TC and the third is from Lone Pine Lake to the Portal on the descent). Two point five miles. I count off 100 steps, stop, rest, sip, continue. Are we there yet? Continue the cycle. Pacing was critical to my success. I got there eventually one step at a time.
...We plan to go pretty slow though.
Sounds like a great strategy! Hey, there is nothing wrong with a 1 mph pace heading up.
Have fun!