Well I'm very sorry to hear about the issues you're having. However it's quite uncalled for to say "I don't know how anyone can play this," because believe me, you're the first person I'm hearing about having issues this severe and this game has a pretty big playerbase at the moment. The game is not "fundamentally broken", sorry to say it.
There's not much I can add onto what Rasip has said above. As far as your newly-salvaged ships immediately consuming all your supplies, that shouldn't happen if you picked up all the supplies provided to you at the station as well as the extra crew, even if you were making field repairs on the way back. Bounty missions give you intel on the biggest contents of the target fleet, so you don't go rushing into death, and bounty fleets can be taken out by other AI fleets if you take too long to reach them. Easy mode is merely a damage taken decrease and damage dealt increase for friendly ships, no other major mechanical changes.
It is worth noting that Starsector is not a particularly easy game, and it isn't for everyone. It's always disheartening to hear about someone finding it unplayable, but that's just the way things are - you can't please everyone in the world. Hey, look on the bright side, you still get a commendation for trying and your feedback is still useful! And you never know, maybe one day when the game is finished you might come back to it and find it playable.
All the best for your future gaming endeavours.