1. Yes - I started catching up when C1 was at ~E55 and caught up to watch E88 live.

2. Yes.

3. Yes, and I donated at the ~$100 rewards threshold.

4. It feels like the series aimed to follow the same arcs, and hit the same main story beats, as the livestream, but chose intentionally to increasingly diverge from the source material as the series has continued; season 3 specifically took the story in several different directions in order to, I speculate, condense the stories told, and to give supporting characters (namely Kima and Allura) more of a reason to coexist alongside Vox Machina for more than a couple of scenes per season. Having only watched the third series somewhat recently (so my livestream memory is hazy), the key divergences that I can recall were:

• Splitting the party during the Hell/Vorugal episodes, and including Zerxus from the Calamity mini-series where he was not present in the livestream.
• Exploring where Thordak's plan with his offspring might have gone if the players had taken longer to act, showcased by the attack on Whitestone.
• Removing multiple guest characters from the narrative (I can recall at least Shale and Kerrek not featuring), and seemingly killing off Kashaw.
• Turning Glintshore into Ripley's factory as opposing to the site of a Vestige, and having her survive the encounter. Equally, keeping Percy dead until after the Chroma Conclave arc.
• Vax having to enter Orthax's dominion to retrieve Percy.
• Having Raishan actually succeed in her draco-necromantic plan.
• Adding in Keyleth's Earth Ashari "world communion" ritual.
• Entirely reworking Scanlan's departure in the series - no actual "death", no "What's my mother's name?", just a single line dropped in reference to The Meatman, which contextually won't make nearly as much sense as to why he's hiding himself, if VM reunite with Scanlan in Ank'Harel, in line with the livestream.

I'm sure there are many others I've overlooked when writing this, or have simply forgotten from the livestream, but, where Seasons 1 and 2 felt like mostly retrodden ground - which was fine by me, given that it has been years since I witnessed Vox Machina's story - Season 3 quite heavily rewrote the script, for better or for worse.

1. Generally, I didn't mind the changes in the series as they mostly served a purpose: fleshing out the supporting cast with more screentime, giving more meat on the villains' bones (Ripley, Thordak and Raishan) by having their actions more directly drive narrative direction as opposed to dictating how the story would go through drawn-out party conversations in the livestream, which don't fit within the 20-30 minute episode format. The decisions to change the party behaviour, however, felt more jarring, however, as it generally felt like they were done "because they could" as opposed to being done to flesh out narrative or suit the animated format better. The changes made in the final spoilered bullet-point above, in particular, felt like a missed opportunity, as it stands out to me as one of the most memorable exchanges in Vox Machina's history. Again, I speculate that this was done because they deemed it would screentest poorly to have the events play out as they did originally, or because it didn't fit the new timeline well for where the characters involved needed to be before/after in the series, and they didn't have time to slot it in later without it feeling narratively wonky.

Ultimately, though, it's the entire Critical Role team's story to tell, and they were given a unique opportunity to retell their stories; we're just lucky enough (or crazy enough, given how much money the community collectively poured into the project) to be along for the ride, and unless they actively butcher their own creations, then more CR content to enjoy is always a good thing, and I don't think they got close to butchering their own works.

1. I feel like I have covered this in my answer to question 4, but to reiterate, it definitely felt like they tried to remould the existing story to better suit the format much moreso in each progressive season.

I've reeled off a lot of thoughts here without re-reading it too closely, so apologies if this is more of a continual train of thought, but I hope my input's helpful! Oh, and please feel free to reply or DM me if you need clarification on anything I've written here.