OSLC: Is it possible to access all attributes and their types for particular work item type?

Resource Shape is what I believe you are looking for which is reached following the discovery mechanism starting with rootservices of ccm.

let me explain from the Services URL obtained through the discovery mechanism:

GET on
    https://localhost:9443/ccm/oslc/contexts/_87qOEKvrEeKxU5AQolS52w/workitems/services.xml

with following headers
    OSLC-Core-Version: 2.0
    Accept: application/xml

and from the response locate the creation factory for the work item type you want to understand and you will see the resourceShape URL

<oslc:creationFactory>
    <oslc:CreationFactory>
        <dcterms:title rdf:parseType="Literal">Location for creation of Defect change requests </dcterms:title>
        <oslc:usage rdf:resource="http://open-services.net/ns/core#default"/>
        <oslc:usage rdf:resource="http://open-services.net/ns/cm#defect"/>
        <oslc:resourceType rdf:resource="http://open-services.net/ns/cm#ChangeRequest"/>
        <oslc:resourceType rdf:resource="https://localhost:9443/ccm/oslc/types/_87qOEKvrEeKxU5AQolS52w/defect"/>
        <oslc:resourceShape rdf:resource="https://localhost:9443/ccm/oslc/context/_87qOEKvrEeKxU5AQolS52w/shapes/workitems/defect"/>
        <oslc:creation rdf:resource="https://localhost:9443/ccm/oslc/contexts/_87qOEKvrEeKxU5AQolS52w/workitems/defect"/>
    </oslc:CreationFactory>
</oslc:creationFactory>

perform a GET on the rdf:resource for oslc:resourceShape and you will see all the attributes of the work item type and the attriubtes data type and more (readonly, mandatory... )

here is a sample for Resolution Date of Defect Work Item Type:
<oslc:property>
    <oslc:Property rdf:about="https://localhost:9443/ccm/oslc/context/_87qOEKvrEeKxU5AQolS52w/shapes/workitems/defect/property/resolutionDate">
        <oslc:valueType rdf:resource="http://www.w3.org/2001/XMLSchema#dateTime"/>       
        <oslc:readOnly rdf:datatype="http://www.w3.org/2001/XMLSchema#boolean">true</oslc:readOnly>
        <oslc:propertyDefinition rdf:resource="http://open-services.net/ns/cm#closeDate"/>       
        <oslc:occurs rdf:resource="http://open-services.net/ns/core#Zero-or-one"/>       
        <oslc:name rdf:datatype="http://www.w3.org/2001/XMLSchema#string">closeDate</oslc:name>       
        <dcterms:title rdf:parseType="Literal">Resolution Date</dcterms:title>
    </oslc:Property>
</oslc:property>

hope this helps...