Facebook Open Graph API: weird behavior of parameter limit while getting a paginated user's news feed

I've written a little script in JAVA, that tests the parameter limit with four different values (10, 100, 1000 and 10000) when querying a user's news feed of Facebook using the Open Graph API and the RestFB client. As you'll see, it has a strange behavior...

Scenario:

public static void main(String[] args) {

    // vars
    DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
    FacebookClient client = new DefaultFacebookClient(accessToken);
    Connection<Post> home;
    List<Post> postList;
    Map<String, Post> postMap;
    int i;

    // limits to test
    String[] limits = {"10", "100", "1000", "10000"};
    for (String limit : limits) {

        // init list and map (looking for duplicate posts)
        postList = new LinkedList<Post>();
        postMap = new LinkedHashMap<String, Post>();
        // get news feed
        home = client.fetchConnection(id + "/home", Post.class, Parameter.with("limit", limit));

        // going through pages
        i = 1;
        for (List<Post> page : home) {
            for (Post post : page) {
                // store into list
                postList.add(post);
                // store into map (unique post id)
                postMap.put(post.getId(), post);
            }
            i++;
        }

        // sort posts by created time
        Collections.sort(postList, new Comparator<Post>() {
            @Override
            public int compare(Post post1, Post post2) {
                return post1.getCreatedTime().compareTo(post2.getCreatedTime());
            }
        });

        // log
        try {
            FileWriter out = new FileWriter("log/output.txt", true);
            out.write("LIMIT: " + limit + "\n");
            out.write("\tPAGES: " + (i - 1) + "\n");
            out.write("\tLIST SIZE: " + postList.size() + "\n");
            out.write("\tMAP SIZE: " + postMap.size() + "\n");
            out.write("\tOLDER POST: " + dateFormat.format(postList.get(0).getCreatedTime()) + "\n");
            out.write("\tYOUGNER POST: " + dateFormat.format(postList.get(postList.size() - 1).getCreatedTime()) + "\n");
            out.close();
        } catch (IOException e) {
            throw new RuntimeException(e);
        }

    }

}

Output:

LIMIT: 10
    PAGES: 7
    LIST SIZE: 56
    MAP SIZE: 56
    OLDER POST: 2009-03-22 14:58:03
    YOUGNER POST: 2012-05-11 15:48:49
LIMIT: 100
    PAGES: 3
    LIST SIZE: 174
    MAP SIZE: 172
    OLDER POST: 2012-01-12 23:01:34
    YOUGNER POST: 2012-05-11 15:48:49
LIMIT: 1000
    PAGES: 2
    LIST SIZE: 294
    MAP SIZE: 292
    OLDER POST: 2009-03-22 14:58:03
    YOUGNER POST: 2012-05-11 15:48:49
LIMIT: 10000
    PAGES: 2
    LIST SIZE: 294
    MAP SIZE: 292
    OLDER POST: 2009-03-22 14:58:03
    YOUGNER POST: 2012-05-11 15:48:49

Interpretations and questions:

1. Obviously, you can't get all the posts a user has had on his news feed since his account was created. Is limit limited?

2. With a limit of 100, 1000 and 10000, I must have had each time two duplicated posts within the whole returned news feed (174 - 172 = 194 - 192). Why? I never saw the same post twice on my personal news feed...

3. With (and only with) a limit of 100, the older post I get was created during the year 2012, meanwhile the other values of limit make the query retrieving a post that was created during the year 2009. I can understand that with an upper limit (1000 or 10000), the query retrieves older posts. But why does a limit of 10 make the query retrieving an older post than a query limited by 100?

4. Last but not least point: I'm not getting the same number of posts. Obviously, the more the limit is high, the more the number of retrieved posts is high. What I thought first, is that the only consequence of a smaller limit was an upper number of pages (which is the case though), but that the number of retrieved posts would not change. But it does. Why? That said, the number of posts seems to converge between a limit of 100 and 1000, because the number of posts is identical with a limit of 1000 and a limit of 10000.

PS: specifying a since and/or a until parameter to the query doesn't change anything.

Any answer/comment is welcome :)

Cheers.

Edit:

This is my best recall:

LIMIT: 200
    PAGES: 3
    LIST SIZE: 391
    MAP SIZE: 389
    OLDER POST: 2012-01-27 14:17:16
    YOUGNER POST: 2012-05-11 16:52:38

Why 200? Is it specified anywhere in the documentation?