Kuroko: Why don't you play in COOP mode if you find the sidekicks problematic? You also won't have to watch the cinematics either and you don't need to worry about the story.
BananaJane: How do you get coop mode working
Few simple instructions for in-general and cooperative play...
Start the game with "+set console 1" if you're not using the community beta patch 1.3. I strongly recommend that you install the community patch since it will fix more issues with the game than cause them. Also if you're not using the community patch 1.3 then disable the V-Sync globally from display driver control panel. That'll workaround the loading screen "ticks" bug.
Enable "unlimited saves" in "Options" menu. In the same menu also disable "Play Intro Movie". It'll cause game to skip the 15 min intro video some people like to complain about in normal SP. Pressing Esc key also skips the cutscenes. However in COOP mode will not even show them to you. It just loads the level.
In "Video" menu set intensity to 3 and brightness to 55~60%. Especially if you're playing the game on a LCD. You should do this even if you play with the community patch 1.3. Without the colours will look wrong, or the game is overly bright and/or dark at certain positions.
Click "Start a Multiplayer Game" in "Multiplayer" menu. Change game mode to "Cooperative" by clicking the arrow next to the game mode name. Choose your difficulty and starting episode. You can skip the ep.1 if you want. But I'd recommend that you also enable cheats by opening the console, typing "cheats 1" and only after that starting the game by pressing difficulty buttons.
The game is not remarkably more or less difficult on Ronin or Shogun, but be aware that if you're playing in version 1.2. The version 1.2 has bugs in the levels in Greece and in San Francisco episodes on Samurai difficulty that makes the game really difficult to complete without use of the cheat codes.
Biggest difference between Ronin and Shogun is the amount of monsters you're facing. On Ronin you're not also getting all XP. On Shogun you can get enough XP to max out all the upgrade levels if you find all secrets and kill all monsters. Final episode on Shogun is considerably easier than on Ronin due the level upgrades you're getting.
I hope you enjoy the game. Daikatana is not a bad game overall. But the execution at times is pretty damn horrible.
P.S. I almost forgot about it... But the patch 1.3 allows now you to play the normal single-player with the cutscenes but you can choose to not play with the sidekicks by ticking an option in the "Singleplayer" menu. And if you get stuck at in normal single-player then press "n" on keyboard and it'll enable noclip mode. Pressing "n" again disables noclip mode.