TCGplayer's condition guide is the standard most sellers use, and there are also plenty of YouTube videos walking through visual examples if you want to see what each condition grade actually looks like in practice
A splash makes you more inconsistent, replacing Doom Blade with Mortify makes you slower
Eevee Grove almost made it into the A Tier, and it could likely shift up a space as the meta continues to evolve over the coming weeks
At the very top however is the holy grail: the 1st edition base set shadowless charizard, which had a ballpark price of 50,000
Its just so far ingrained in what the format is at this point
Relentless Rats is a fun, if not exactly viable, strategy for building a Commander deck, and the same might be true for the pups if Ravensburger officially supports their own version in the near future