So killing stuff is worth the same, but hacking/lockpicking/speech challenges is worth more on hard or very hard?
That wouldn't make much sense, seeing as if the difficulty setting works the same as in Fallout 3, only combat will become more harder due to higher difficulty, and therefore, logic should dictate that, if the experience gained from anything increases with difficulty (Though personally, I wouldn't want it to for anything. What difficulty I play the game on should be a choice I make based on what difficulty level offers a challenge I'm comfortable with, not how much experience I want from combat.) it would logically only apply to combat. But I'm going to assume what this means in terms of lockpicking and hacking is not that the difficulty setting effects the amount of experience gained from it, but that the difficulty of the lock or computer does. I.e., picking a hard lock gives more experience than picking an easy one, it would seem logical for me, seeing as stronger enemies usually give more experience, it doesn't seem unreasonable that harder locks and computers would too. Of course, since I don't have the game yet, I'm just speculating, if I'm wrong, someone who knows this can feel free to correct me.
I'm glad to know that difficulty setting doesn't effect the amount of experience gained from combat, though, I want to be able to choose a difficulty setting that offers a challenge I'm comfortable with without needing to worry about leveling becoming too fast or too slow for it.
I wouldn't stress over it too much. There's TONS of things to do for xp. I'm more worried about hitting the level cap well before the end game like I did in Fallout 3.
I think that's exactly the problem, a lot of people found Fallout 3 too easy so they played it on higher difficulties, the problem is that, aside from some still complaining that it's too easy even on very hard, increasing difficulty made you gain more experience, and even on normal difficulty, you could still easily reach level 20 before you're finished with the game, increasing the difficulty just made this happen sooner.