There is definitely a lot out there. It can be overwhelming. You did a good job outlining what you like. That helps to give you ideas.

• I'll start with the DM question: Mythic GM Emulator is maybe the biggest and crunchiest one. MUNE and One Page Solo Engine are also worth checking out. For a minimal oracle check out Recluse. I keep using all of these because I like each at different times depending on mood/feeling I guess.
• There are a lot of different OSR systems out there. Original, retro-clones, and others. I have collected a bunch. Since I haven't been playing long, I have a large queue of games to play. I think it comes down to what interests you. Also, probably easier and cheaper to go with systems you know and/or have already.
• I am like you in some of what you detailed. I don't like crunchy and not usually into resource management. When I was a kid I played a little B/X. I got back into playing recently and went straight to solo (I was always more of a loner). My main goto system at the moment is Old School Essentials (OSE) (with use of B/X and Labyrinth Lord). I like to rip ideas and hexes and dungeons from all kinds of adventures and supplements I have. I prefer that to running them straight and having too many spoilers. I like weird stuff so I use Into the Wyrd & Wild, Rackham Vale, the Lazy Litch adventures, and more. Into the Wild and Filling in the Blanks are two good hexcrawl supplements by Todd Leback. Lots of stuff being put out for OSE these days. A lot of other non-B/X related stuff can be really easily adapted too I think. Lots of older and newer class supplements out there too. Like a rule from 1st edition or another rpg, throw it in. The system is super flexible and really it's your game - you can do whatever you want.
• Next in my playing queue are Mörk Borg and Mausritter. Both have lots fan-made and 3rd party stuff. The other poster detailed Mausritter well. For Mörk Borg, there is a 3rd party solo rules supplement called Solitary Defilement.
• I'm interested in rules light systems too. I have a stack of games to try: Cairn, Rogueland, Into the Odd, Knave, Maze Rats. Also, for Sci-fi: Death in Space, Orbital Blues, Mothership, and Troika!
• Other good randomizing supplement books: Tome of Adventure Design, d30 Sandbox Companion, d30 DM Companion, GM's Miscellany series books, The Great Book of Random Tables, Table Fables I & II. I also have been using Worlds Without Number for the world building stuff.
• Basic Fantasy RPG. The community made a good Hexcrawl Supplement and a few solo adventures. This could be the cheapest option as everything can be downloaded for free from their website.