Is this like, "I foresee a crossroads in your future"?

Keep in mind that the goal of DCC RPG is not to simplify 3E. The primary goal is to re-envision what D&D
could have been if the creators focused their energies on adapting their inspirations to an existing rules set, rather than building everything from scratch. The early days of the hobby have an interesting mix of creative inspirations (e.g., Appendix N) and rules inspirations (e.g., wargames evolving to Chainmail evolving to OD&D). What if there were no need for the rules evolution - what if Gygax and Arneson (or, say, someone else more modern) took the same set of creative inspirations and applied them to an existing rules set?
So, the concept is not "let's make 3E simpler." The concept is, "let's make a modern rules set reflect Appendix N accurately" (as well as other important D&D influences, such as the Hammer Horror movies, but I'm bundling that with Appendix N). This requires re-reading every book in Appendix N (which I've been working on for a couple years), then applying rules -- existing where possible, new where not -- to that body of work.
Now, with that said, some comments on your notes:
Alignment: Clearly integral to an old-school game, as its conceptual antecedents figure prominently in Appendix N. Poul Anderson created the Chaos vs. Law concept, later adopted by Michael Moorcock in his Elric works and eventually codified into D&D as the nine-grid we know so well.
Saving Throws: Can't live without them, as evinced by REH's Conan works. Conan almost always makes his saving throws.
Death, Dying, and Healing: Healing is actually an interesting one, as there are many "OSR scholars" who believe the cleric is a Gygaxian invention and doesn't figure prominently in Appendix N. There are clear examples if you read broadly enough - Poul Anderson's
High Crusade features a cleric as a main character (and his other works have clerics as important characters), Margaret St. Clair's
Sign of the Labrys has a cleric-themed subtext, Sterling Lanier's
Hiero's Journey features a strong cleric archetype, Lord Dunsany's
King of Elfland's Daughter has a cleric as a tertiary character - but most of these evince turning abilities (often against fey, not undead!) rather than healing skills. Only in
Hiero's Journey have I so far found a strong clerics-can-heal theme.
Condition summary, environment, breaking items, attacking objects, hazards & obstacles: Not as important to me...simply because versions of these rules didn't exist until, what, the early to mid 80's? And we all played D&D just fine without them for the first 5-10 years of the game.
Character classes: Which ones were in Appendix N?

Conan = fighter, thief. Elric = fighter, magic-user. Vance = lots of magic-user characters, and then you have Cugel who was a thief. Fafhrd & Gray Mouser = thief, possibly fighter.
Three Hearts, Three Lions = arguably the inspiration for the paladin class but potentially a fighter or cleric model as well. ERB / John Carter of Mars = clearly the archetypal fighter. Lovecraft = magic-users and evil clerics. Merritt = fighters and magic-users/clerics. Saberhagen = magic-users. Zelazny = fighters, weak magic-users. I don't need to go into Tolkien. So I guess we've got fighters, magic-users, clerics, and thieves? As for races, most of the elves in Appendix N are fey-like creatures who hate the touch of iron...
Feats and skills: Conan and Elric seemed to have a lot of feats but, again, if we didn't need them in 1974, we don't need them now.
That's all for now...except to note that magic is a very different conversation. For all the people who refer to D&D magic as "Vancian," how many people have actually read all the books in Vance's
Dying Earth series? And then read the
Harold Shea series by de Camp & Pratt? At its core, D&D magic has a greater resemblance to de Camp & Pratt than Vance. There are unmistakable allusions to (and outright reprints of) Vance's work in D&D, which earned the term Vancian, but it was in the
Harold Shea series that the word "somatic" first appears, and we get the "ingredient system" that D&D spells became by AD&D. To Vance we owe the memorization system, and the term "prismatic spray," and not much more. But both Vance and de Camp-and-Pratt feature something that's missing from D&D now: unpredictable spellcasting. Remember when Harold Shea tries to summon a dragon, and actually summons 1/10 of a dragon (a pseudodragon)? Then on his next casting he accidentally gets 100 dragons? And Cugel the Clever suffers similar misfortunes when trying to cast spells against his nemesis Iucounu? Creating a magic system that accurately reflects magic as it's depicted in the foundational works of D&D is
not the same as what D&D spellcasting has become. More on that another day...