Yes, it probably would be a good idea if when selecting an option in dialogue, you get to see your modifiers to that skill. That's a very good idea.

I think the "number to reach or exceed" displayed already takes into account your modifiers. So if your total amount of modifiers to the roll is +4 and you see that you need to beat 8 on the die, it means the actual DC is 12. If your total modifiers was +3, it would say you needed to beat 13 on the die, and so on.