Collect triples from Wikidata using SPARQL

I would like to collect triples (subject, predict, object) from a Wikidata entity (e.g. Helen Keller). Currently, I have a query as below:

SELECT ?wd ?wdLabel ?ps_Label ?ps_Description WHERE {     
  VALUES (?item) {(wd:Q38203)}    
  ?item ?p ?statement .   
  ?statement ?ps ?ps_ .    
  ?wd wikibase:claim ?p.   
  ?wd wikibase:statementProperty ?ps.   
  SERVICE wikibase:label {          
    bd:serviceParam wikibase:language "en".    
  }         
}

I have two questions about this:

It seems that many meaningless triples will also be listed, such as properties ("CONOR.BG ID", "National Library of Ireland ID"). But all I want is the crucial triples. Can I filter them directly, or is there a score I can rank?
The above query retrieving triples seems the entity acts as a subject, not an object. In other words, the format (Helen Keller, ?, ?) can be retrieved, not (?, ?, Helen Keller). But I intend to collect all triples even though it is an object entity.

Solution

If you just want to exclude identifiers, you can add the constraint:

FILTER NOT EXISTS {
     ?wd wdt:P31/wdt:P279* wd:Q6545185 .
}

this is excluding all the properties that are instances of (subclasses of) unique identifier (Q6545185)

I would suggest you to just do another query swapping ?item and ?ps_. In case you want to achieve this with a single query, you can replace

   ?item ?p ?statement .
   ?statement ?ps ?ps_ .

with

   { ?item ?p ?statement .
     ?statement ?ps ?ps_ . }
   UNION
   { ?subj ?p ?statement .
     ?statement ?ps ?item . }

and also select ?subj in order to mark the tuples referring to the "inverted" relation.

The resulting query would be as follows:

SELECT ?subj ?subjLabel ?subjDescription ?wd ?wdLabel ?ps_Label ?ps_Description WHERE {     
  VALUES (?item) {(wd:Q38203)}    
  { ?item ?p ?statement .
    ?statement ?ps ?ps_ . }
  UNION
  { ?subj ?p ?statement .
    ?statement ?ps ?item . }
  ?wd wikibase:claim ?p.   
  ?wd wikibase:statementProperty ?ps.   
  SERVICE wikibase:label {          
    bd:serviceParam wikibase:language "en".    
  }
  FILTER NOT EXISTS {
    ?wd wdt:P31/wdt:P279* wd:Q6545185 .
  }
}
ORDER BY ?subj ?wd