I dunno, 20-25, I had to finish it because WoW WotlK is out tomorrow. There were like 6 or 7 big sidequests I didnt do, but I did some of the harder ones. The game really sweeps you up in the final main missions. I did get 590 of the achievement points and hit level 20.
For power armor just find the citadel and have them train you, then you can use whatever you find.
Mud: Fission battery for Ridley's quest? Its on the same floor as the resturant, there's a ruined robot. They tell you that! Even the flaming sword I made from parts wasnt that hard. Most of the junk vendors sell the parts. Just fast travel between all the vendors and get what you can from them, before looking for locations that could have the part.
Why did you expect a journey through a post-apocalyptic wasteland to be easy?