Nothing in the series gives away major plot points of the other novels
Not major plot points necessarily, but some of the books read very differently if you've read the Dark Tower vs. if you haven't. Hearts in Atlantis
, for example-- readers of Wolves of the Calla
will recognize the antagonists, and those who aren't there yet won't. Or 'Salem's Lot
-- you're going to know a lot about the basic plot and the character of Father Callahan if you've finished the Dark Tower first.
The difference between King and Tolkien is that while Tolkien consciously planned each piece of Middle-Earth writing (bar The Hobbit
) as part of an internally-consistent mythic cycle, King's design is much more haphazard, and if you're expecting anything like the degree of common theme, worldbuilding, and tone you get in Tolkien, you'll be disappointed. 'Salem's Lot
as originally conceived had nothing to do with the Dark Tower, so when you read it you're not going to find any connections to the series as you know it. It'll only be when you get to Wolves of the Calla
that you understand how it ties in, to the extent that it does. Same for "Everything's Eventual," except it only connects in the final Dark Tower book. It
has a couple very loose metaphysical connections to the Dark Tower, but not much else-- I don't know if King had planned those in advance either.
Anyway, I'd say your current list looks reasonable. It'll be a slow start in terms of "mythos" elements, but that's not necessarily a bad thing. I assume you're planning to read (or reread) "The Little Sisters of Eluria" somewhere in there as well. You could honestly drop It
without losing much (as far as the tapestry-- it's a fine novel on its own merits, although a little peculiar in many ways), but the rest is pretty strongly linked. (Not so much The Talisman
unto itself, but Black House
retroactively draws it into the tapestry.)