Welcome
! I'm into most of the stuff you've mentioned and a lot more...
Group recommendations, okay, let's go per prog sub-genre
1. Art Rock - Rush, Kansas, Anekdoten, (later) Porcupine Tree
2. Canterbury/RIO/Avant-prog - Caravan, National Health, Gong
3. Electronic - Tangerine Dream (there are more of course, but TD are the only ones I'm familiar with to any extent, 'Ricochet' is a great album!)
4. Experimental/post rock - Mogwai, Radiohead, Godspeed You Black Emperor, Explosions in the Sky, Sigur Ros
5. Fusion - Frank Zappa (although he's a genre all of his own), Alan Holdsworth, Brand X, Mahavishnu Orchestra, Return to Forever
6. Italian Symphonic - Premiata Forneria Marconi (as with Tangerine Dream)
7. Kraut rock - Can, Popol Vuh, Amon Duul II
8. Neo progressive - Marillion, Twelfth Night, Discipline, Pendragon
9. Prog folk - Jethro Tull, Mostly Autmn, Iona, Karnataka
10. Prog metal - Opeth, Dream Theater, Cynic, Symphony X, In the Woods...
11. Psychedelic/space rock - Hawkwind, (early) Porcupine Tree, Gracious, Ozric Tentacles
12. Symphonic prog - Camel, The Flower Kings, Spock's Beard, Focus, Gentle Giant
13. Zeuhl - Magma (as with Tangerine Dream and Premiata Forneira Marconi)
There are mp3s from almost all of these artists available here; there's about 8 Dream Theater mp3s, so you can make up your own mind about them.
And don't worry about the lack of quick replies here, usually you have to wait for a day or two.
Have fun
!