Alright so I have some questions about this one, related to my apparently incredibly exceptionally horrible 20 hour experience with Dark Souls.
1) Is there some kind of sensible layout to the world? I know DS1 was all interconnected, but that was often if you just happened to find tiny little corners that give you and elevator or something. I had an awful experience running long stretches in 4 different directions looking for just one damn bonfire then someone would say afterwards "Oh, you could have just gone to [describes tiny obscure corner with shortcut to a fire]"
DS3 makes use of shortcuts in much the same way as DS1, but they're more obvious and they don't tend to go between different areas, only between different parts of the same area. Unlike DS1, however, in DS3, the ability to warp between bonfires is available from the start, which makes traveling much faster.
2) Can you turn off online? I had a particularly awful run once where I went on a huuuuuge hours-long journey doing really well for once, eventually barely surviving the giant rat boss with no potions, getting cursed by some bug thing, and then about 5 feet from a bonfire I finally found I was invaded by a ridiculously OP person who one-shotted me after I got like 15 hits on them that did almost nothing. That is some bullshit and I never want it to happen.
In DS1, this only happened when you were in human form after restoring it at a bonfire using consumable humanity items. In DS3, Embers are a consumable item that boost your max HP by 30%, but open you up to invasion until death. You are otherwise not able to be invaded. You can also turn off online functions entirely, but you won't be able to read or leave messages.
3) Do you still turn into a zombie when you die? I spent most of my time in that form as I died a lot and it was kinda lame after spending time in character creator.
Only if you pursue a certain sidequest chain, and even then, it can be undone.
4) If you die at a boss do you have to go all the way from the last fire, and if so, are fires closer to bosses? I must have tried Capra Demon like 30 times trying to figure out a working strategy before finally giving up and just watching a youtube of a good one. Every single retry I had to run through the sewers from the main bonfire, killing all the monsters along the way. It was a really lame, redundant, unchallenging waste of time for just another possibly-five-second chance at figuring out the boss.
Shortcuts are a big part of this. If you make effective use of shortcuts and run past enemies, you will rarely have to run for more than 30 seconds to get back to a boss.
5) Do you still spend souls you collected to level up yourself or weapons, requiring you to not die to keep that progress until you saved up enough? I suppose I'm okay with that aspect, provided there are ways to grind if you have to after a death, just as long as it isn't too ridiculous. However I would like to know if it is a prominent aspect. I really prefer games where you start with all your abilities and it is the performing challenge itself that is hard and you can just go for it, not how smartly you develop your character, requiring a lot of additional study outside the game.
You use souls to level yourself up, buy items, and upgrade weapons, although for the latter the primary resource is Titanite, which is not lost on death. Trying to retrieve your souls upon death is definitely important, but you are always able to grind. As for character development and challenge, skill is far more important than your level or equipment. People have beaten the game at level 1 (though you'll still need to upgrade your weapons to be able to do any sort of reasonable damage later on). Don't worry about potentially messing up your build - you can respec 5 times per game cycle (as in 5 times in a new game, then 5 more times in a new game+ in the same file, then 5 more times in NG++ etc.