Whoops...

P4, last sentence, very bad wording; it should 
be "People have to realise that original IP rights are 
maintained regardless of location or medium."  
That is, rights are not automatically transferred with an 
object, and intellectual  property is independent of 
material goods (Title 17,106 and 202). Sorry. 
^^;

Basically, yes.  If you don't have permissions from 
the studio who owns the IP rights of an anime, you're not 
supposed to post material except in strict fair use such as 
criticism/reviews, newcasts, and some other things.  This 
also depends a bit on the "no reproduction in whole or part" 
clause of many creative works; I think the 'derivative works' 
clause in section 106 can also be used to address digital 
versions.  Someone mentioned that CLAMP explicitly asked 
fans not to post their material on the web - and it is within their 
exclusive rights to control their art. 

The 
problem with "fair use" doctrine is that it's not statutory - 
the concept is really case-law (case-by-case determining), to 
it's quite fuzzy as to interpretation. For instance, the 
'substantial portion' requirement in fair use is pretty 
flexible, so you need not reproduce an entire film on the web to 
get into trouble (another provision of the 
whole/part/derivative  requirement on some things). 

As 
for the 'nonprofit' thing - again, it doesn't matter if 
something is passed around freely for it to be illegal.  Yes, 
fansubs are illegal.  The nonprofit issue is actually only 
part of the 1st and 4th factors of the fair use section 
(commercial vs. education, effect upon potential market or 
value of cr'd work). Many of the sources I've seen will cite the 
'educational' provision of the fair use section (Title 17, 
107) in its narrowest terms, that is, educational only for 
nonprofit educational institutions.  Even universities 
apparently can get into a bind in using material in their 
classrooms for educational purposes. (An example is how one 
gets the MPLC license for showing films in public.) Of course, 
this is probably for preventative measures since it's easier 
to sue a university than an individual (not that it doesn't 
happen).  

Um, hope that clears things up a little. Maybe. 
Remember, I'm not an attorney, better to ask someone in a legal 
firm if you really must know in no uncertain terms. ^^