Some comments about the relationships between rdfs:subPropertyOf and rdfs:domain(rdfs:range)

Hi,
 
I have some comments about rdfs:subPropertyOf:
1) if  (R rdfs:subPropertyOf S) 
     (R rdfs:domain C1)  (R rdf:range D1)
     (S rdfs:domain C2)  (S rdf:range D2)
  can we infer that  (C1 rdfs:subClassOf C2) && (D1 rdfs:subClassOf D2)?
 
I believe the result can be easily inferred by the RDF Model Theory, but
there is no rule in the RDFS closure rules
to show this inference. 
 
2) rdf schema allows one rdf:Property has multiple rdfs:domain and
rdfs:range,  and  the resulted domain and range is
considered as intersection. But RDF schema specification didn't say much
what about have zero rdfs:domain or rdfs:range,
this arise some confusion.
 
a)       is zero rdfs:domain or rdfs:range declaration is legit in rdf
schema?
b)       If zero rdfs:domain declaration means that the property's
domain is rdfs:Resource, there is a problem: if the property's
superproperty 
's domain is declared as Class C1, then we can conclude the propery's
domain is a subclass of C1, but not rdfs:Resource.
c)       What is the meaning of zero rdfs:range declaration?
 
 
Thanks!
 
Liu shengping