The FtpGetFileSize method shown in the following code gets a file's size in bytes. The uri parameter gives the full path to the file as in ftp://www.somewhere.com/test.txt.

// Use FTP to get a remote file's size.
private long FtpGetFileSize(string uri, string user_name, string password)
{
    // Get the object used to communicate with the server.
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create(uri);
    request.Method = WebRequestMethods.Ftp.GetFileSize;

    // Get network credentials.
    request.Credentials = new NetworkCredential(user_name, password);

    try
    {
        using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
        {
            // Return the size.
            return response.ContentLength;
        }
    }
    catch (Exception ex)
    {
        // If the file doesn't exist, return -1.
        // Otherwise rethrow the error.
        if (ex.Message.Contains("File unavailable")) return -1;
        throw;
    }
}

This code creates an FtpWebRequest object to work with the file. It sets the request's Method property to GetFileSize and gets a response. The only trick here is that the file's size is returned through the response's ContentLength property.

The FtpGetFileTimestamp method shown in the following code gets a file's creation date and time.

// Use FTP to get a remote file's timestamp.
private DateTime FtpGetFileTimestamp(string uri, string user_name, string password)
{
    // Get the object used to communicate with the server.
    FtpWebRequest request = (FtpWebRequest)WebRequest.Create(uri);
    request.Method = WebRequestMethods.Ftp.GetDateTimestamp;

    // Get network credentials.
    request.Credentials = new NetworkCredential(user_name, password);

    try
    {
        using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
        {
            // Return the size.
            return response.LastModified;
        }
    }
    catch (Exception ex)
    {
        // If the file doesn't exist, return Jan 1, 3000.
        // Otherwise rethrow the error.
        if (ex.Message.Contains("File unavailable")) return new DateTime(3000, 1, 1);
        throw;
    }
}

This code creates an FtpWebRequest object, sets its Method property to GetDateTimestamp, and gets a response. The trick here is that the file's timestamp is returned through the response's LastModified property.