I don't think the dash lightbulbs need enough juice to actually make a significant/measurable difference in alternator load/fuel consumption. But a LED dash sure would make a good modding project anyways!
As for deactivating the power steering, dunno if it's adviseable. My take on this is that while you don't use it, it doesn't take that much engine load (well, some, to an extent). The more energy needed to turn (low speed), the more the pump increase load. Add some newer variable steering assist technology (barely/no assist at high speed) to the mix. Removing the PS would probably result in a small MPG difference on highway driving, but *could* be worth it in urban situation.
Also, not all cars are equal. I had a VW Fox without power steering. Turning the wheel was quite manageable even while parking. I once lost my engine and all power-thingies in a '97 Jetta (not much a bigger car), on the highway. Steering on the exit off ramp was
way harder than turning the wheel on a stopped Fox. The reason is that cars designed without power steering have a steering rack geared differently, to minimize effort. Not trying to discourage you, but keep that in mind. As said up there, better try it out on "closed circuit" before hitting the road.
I'll bet you're bored on long trips, driving without radio, eh?
