Justice is a fan-made global mod.

No, you can't. The incorporeality coefficient is common to all incorporeal creatures, and I wouldn't advise changing it, as the rule "cannot have 3 hits or 3 misses in a row" will still work, but it will only confuse the player.
Having very low HP means you don't want to reduce it further, but simply giving a super ability that increases HP by 2 levels (almost doubling it) is possible.