1) Do Changelings have to follow the hospitality rules if they cross a threshold uninvited? I would guess not since they're still part human and have free will. But, then again, Wizards are human and thresholds affect them.I think you're conflating two very different things, here. A threshold will affect their magic, the same as it does for any other magic that crosses without invitation. To be fair, Changelings and other Un/Seelie, et al, that are powerful enough to do this in the first place are likely to be mostly unfazed by anything short of VERY powerful thresholds.
The zombies and frog demon can be explained by the concept of a threshold being able to be assailed and, eventually, broken down. Creatures that are barred from passing can try to destroy the threshold so they can enter. At least, IIRC how those scenes went. It's been a while since I read the respective books. And the book does provide good rules for using a threshold as a block that has to be bypassed or a barrier that can be attacked and weakened.
How It Works
A threshold can operate in four different modes:
as a block, a target, a suppressor, or a source of
harm.
As a block: In the most basic form, a threshold
acts as a free-standing block (page 210) that
usually doesn’t need to be maintained by a character.
The threshold has a strength level (adjective
difficulty as determined below) that opposes
any affected supernatural actions. As a block, it
sets a minimum difficulty level for the success of
those actions.
As a target: Some creatures affected by the
block will be unable to do anything to bypass
it or weaken it. Other more powerful creatures
may be able to assail a threshold (usually only an
artificially created one) or tear it down. In such
a case, the threshold’s strength may be treated
as a stress track (one box per level, with consequences
a possibility). The threshold’s strength
drops as it takes stress hits.
As a suppressor: Many spell effects and some
supernatural abilities will erode or completely
disappear if they are carried across a threshold,
unless specially exempted (such as by invitation).
In this case, all affected abilities and spell
effects lose a number of shifts of effectiveness
equal to the strength of the threshold. If the
spell affected has multiple parts to it, how the shifts are spread around may be determined
(and changed) on a case-by-case basis as decided
by the GM (though this should be done with
plenty of input from the affected player). In the
case of attack abilities, this most often manifests
as a reduction of the damage bonus provided,
acting as a penalty to the actual attack roll only
after the damage bonus has been reduced to
zero. If it isn’t clear how to “reduce” an ability,
then these reduction shifts might be spent on
improving opposing effects and efforts.
As a source of harm: Creatures of pure spirit
and other such entities are particularly vulnerable
to crossing thresholds. They may actually
take damage from crossing one, facing an
attack from the threshold’s strength during
every exchange. The GM may choose either to
consider the threshold’s attack to be equal to
its strength, or to roll and treat the strength as
an attack skill. Few creatures manage to hang
around long in the face of such conditions,
especially when their defensive abilities offer
no protection whatsoever against this attack.
Depending on the nature of the vulnerability,
they may end up rolling a Mediocre default in
defense against the attack. While some might
be allowed to use a Conviction defense, even
weaker thresholds will force such a creature to
retreat or dissolve, if given enough time.
How would that apply to, say, a Werewolf though? Reduce any bonuses he gets from his Inhuman Speed and Inhuman Strength by the amount of the threshold?Or require a discipline check against the threshold to change form - one or the other. A shapeshifter that explicitly turned into a real, physical, ordinary wolf wouldn't have their physical abilities reduced at all, though.
There is precedent for a threshold only stripping away some powers though. From the same wiki article I referenced earlier, in regards to Ghost Story:I don't agree with your interpretation here. Yes, it makes it harder for the WCV to access those powers. Does that mean those are the only powers limited? No, just that they're the ones Dresden mentioned that time.
Or require a discipline check against the threshold to change form - one or the other. A shapeshifter that explicitly turned into a real, physical, ordinary wolf wouldn't have their physical abilities reduced at all, though.