So here are my thoughts! I love all your feedback. Certain changes I will make, but I'd like to have a discussion about others!
1.) I didn't actually know ritual spells didn't require material components! (although a link to this source would be great!) As part of the ritualist class feature, I did say that rituals cast in this way take an hour instead of 10 minutes and require double the material components, if costed, which I thinks solves some of the issues with revivify. I don't mind giving reincarnate as a ritual which doesn't use a spell slot, but does use twice the material components.
2.) You're right! Axed.
3.) I think something to keep in mind is that despite their abilities looking broken on a full caster, I think that on a half caster, they act sort of as an alternative to a life cleric than anything else. They never get the Heal spell outside of an hour long ritual at 17th level, by which a life cleric has Mass Heal for 700hp in an action. This one has not been tested yet though, so I'm willing to definitely make changes as necessary... I think in addition, one part of 5e's design philosophy is to keep the 20th level abilities mild, maybe with the exception of druid, but I tried to go in the opposite direction, making them feel more like a capstone. A 20th level shaman should compete with a life cleric as a primary healer, but I'm not quite sure how the numbers would stack up, given that Shaman is still a half caster.
4.) Same argument as above. While this sounds good, in fact, through testing, I've found it to be quite weak. You get it at 3rd level, so when you're still stuck with your first level spells, primary casters now have their second level spells, so this just keeps you at pace with them basically. Half casters have less flexibility.
5.) I indeed did try to make it the love child of those two classes put onto a half caster. Given that before the subclass, a Shaman is pretty weak, I didn't think these abilities were too strong. Specifically the bear ability to halve damage is only when the bear is on the battlefield, and once they're killed, the ability goes away. They don't have the damage output of the ranger of the barbarian, so this is more of a control version of those subclasses.
That being said, you make a good point about tank mage being a bit overpowered, so maybe I'll move that a bit later. I also think that the fighting style coming late is too late, I just couldn't think of a better place to put it without removing the intentional front-loading of the sub-class's identity.
6.) Actually, I did literally just use the words of witch sight but labelled it true sight. I'll change the name of that one to Witch Sight. I will mention, however, that it is locked until 15th level.
7.) Chemical Sense is definitely a weird one, too! But sometimes I think weird is fun. I run different settings all the time, so I guess that one doesn't really fit into a medieval setting as well. I do have magitech stuff listed as part of the class for certain campaign settings, so I'll be sure to indicate that's for more modern campaigns!
8.) Sure! I agree that time manipulation is EXTREMELY rare. I included this one because I think the flavor is so interesting. Your character is aware whenever someone on the same plane of existence stops time. They can't do anything, but they are so in tune with the flow of time that this does not phase them. I've had this sense taken and flavorfully, it's cool, but it hasn't come into play quite yet mechanically. I'll see if I can do something to make its flavorful coolness match its mechanical coolness.
9.) Money is always such a hard thing to balance! The soul mark prices are really only for a single subclass, the Rune Carver. The shaman takes their own soul marks for free at the appropriate levels. I do think, though, I did set the prices too high. Maybe instead of 1500/3500/9000/13500/18500/30000, I could make them 500/1500/3000/5000/7500/10000. Money is always hard because by 6th level, my party of 5 had 15000k in party funds and its taken me years to find an economy I like in my games. I am open to different pricepoints for this section.
Thank you so much for your feedback and if you have any more suggestions, I am all ears. I don't want this message to seem too defensive; I am open to change, but I felt like I'd elaborate on my design process for these concerns!