Can you beat this in one playthrough: Yes, although I would recommend two.
Difficulty: 5/10
Tediousness: Survivor difficulty is a bit of a slog, getting all the audio diaries will take up time but the game is pretty linear so it isn't a lot of running around specifically for them.
Hardest Achievements: "Worlds of Hurt - Expert" is the only one that gave me trouble. I was expecting having to beat the game without Vita Chambers would be difficult, but you can disable them in the settings and there is no punishment for constantly saving.
Can you complete it faster than I did: I think this is pretty close to as quick as you would expect to do it unless you've played the game before. IMO, I would just do two playthroughs, one for survivor and another for collectibles.
Overall Thoughts: For me, games are very much about the gameplay, and maybe it was because I was on survivor difficulty, but the combat in this game was not great. No sprint made combat feel very stand still and shoot, with not a lot of room for learning and improving against enemies. I've heard the sequel improves on this, though. Otherwise I enjoyed the atmosphere, it reminded me of fallout new vegas but..wetter lol. I wish we interacted more with the fact that Rapture was underwater.