Interesting list. I've read most books in it. There's a bit too much listening to literary critics in there - e.g. Mieville is skilled writing, but it is not SF - not really.
Add in Neal Asher for the 2000s. Breakneck action space opera, wily AIs, disgusting wildlife, rarely a dull moment, Banks on speed.
Also, almost any Vance is bound to be enjoyable, after you acquire the taste (the P.G.Wodehouse of SF, not that it is comic, more of a sardonic tone).
And yeah, Lem, The Cyberiad, the non-existing-book reviews, whatever. Also, Pierre Boulle, amazingly unknown in spite of the movies (Les Jeux de l'esprit should be mandatory reading in some sophomoric circles.)
Nope. Remember that Project Gutenberg hosts books which have lapsed into the public domain. That's not true for a lot of the stuff mentioned. (A decent collection of Van Vogt is available through Baen Book's Webscriptions program, though it lacks classics like Slan.)
You will find the occasional oddity: a couple of Samuel R. Delany's early Ace Double publications just popped up, and Chip is still very much alive. Chip has been in the business a long time - if they've lapsed into the public domain, it's because he allowed them to.
(It is weird when you see stuff appearing on PG by people you know/knew - Delany among the living, and Terry Carr and Laurence M. Janifer among the deceased.)