I find starting from scratch to be infinitely easier, especially for a home campaign. That doesn't mean I won't use modules as a resource, but acting making whatever WotC decided to do workable with my collection of misfits is juice not worth the squeeze.
On further thinking about it, it doesn't really matter if steampunk is anti-capitalist or whatever. The true defining feature of cyberpunk (of which steampunk is basically a subgenre according to Jeter) is that it is about technoshock. And steampunk can do that.
Does most steampunk? I don't...
I think you are overthinking it. Hard is "hard" for people without a bonus or advantage based on class or background. Hard might be "easy" for someone that has both. The DC doesn't change.
They are also insane, by definition, so stories like them seeking out a reincarnated lover or kidnapping a priest to resurrect a lost confidant, or whatever.
I think lichdom is less about power and more about immortality. I would think most liches stay hidden in their fortresses or demiplanes, conducting unspeakable magical experiments, and occassionally sending minions out to find subjects for said experiments.