Hi, yes, if you've found a good farrier, hang on to him & treat him well!!
As keeping hooves in good nick is even more to do with management, feeding, etc, not to mention there are different theories & approaches, I do suggest people educate themselves on the principles of hoof health & function & not just take the word of whatever expert they employ though.
So on that note, a few comments on what you wrote....
he fixed the angle on her left front heel by three degrees (apparently there was a difference of five inches so he fixed it as much as he could without taking too much off her feet). There was a huge difference in how Indie stood once he fixed it, she used to keep that leg forward but within a few minutes, she was comfortably standing with her legs squared!
I gather you mean 5 degrees, not 5 inches?!
Horses are often uneven, often called 'club footed' when it's quite obvious. This can be due to innate conformation(none of use are perfectly symmetrical), so called 'contracted tendons', posture & grazing stance, injury, bad farriery, etc. Depending on the cause and longevity of the difference, it is often not a good move to 'fix' it & try to make feet match. If/when it is appropriate to change it, it should be done gradually & there's usually more to it than just trimming - eg. bodywork, protecting/supporting feet to allow better use, management changes if it's due to grazing stance, etc, etc.
He also recommended that we switch her steel shoes to aluminum shoes because it'll create less impact on her joints when she moves because they're more lightweight.
Yes, the lighter the shoe the better IMO, but studies that have been done show little if any difference in concussion between different metals. It's unfortunately one of those effects that seem to be innate to peripherally loading hooves with metal. If you're concerned about joint injury, I'd suggest looking into hoof boots when protection is needed, rather than conventional rims.
He also recommended an anti-inflammatory for her legs because there was a bit of heat in the left front,
Yes, may be a good move, especially when changing angles, so possibly straining joints. But I would want an equine vet's opinion before giving generally & remember also that anti-inflams have side effects too, particularly on the gut, particularly if given in more than the short term. I would suggest feeding a probiotic whenever drugs such as this are given.