The answer is yes to both questions:
Question 1: There are two ways to import data into OJS quickly. Expedited Submission Process
This is recommended for smaller jobs (e.g., 1 - 10 articles).
First, make sure you are logged in as a user that has the role of both an Editor and an Author.
When you make a submission, you will be given the option to move the file directly into copyediting, where you direct it to an existing issue, bypassing all of the standard OJS reviewing and editorial steps. This requires that you have already created the issue as an Editor, and that you have a ready-to-publish PDF or HTML file to upload.
The file will immediately appear in that issue.Import an XML File
This is recommended for larger jobs (e.g., 10 or more articles).
You can create an XML file that describes all of the issues and articles to be added to your new journal, and import it as the Journal Manager. For details, see:http://pkp.sfu.ca/files/ImportingData.pdf
and the following thread: viewtopic.php?f=2&t=2600
This will automatically create records for each article, and all of the issues and volumes for your journal. There can be some initial time spent creating the XML file, but once it is completed, you will have your content loaded in seconds.
Question 2: Changing the order of published articles
Log in as an editor. Under the editor's User Home - Issues heading, click on the "back issues" link. Choose the issue that you want to edit. You'll notice up and down arrows beside each article (and each section, for that matter); click on those arrows to move the respective item up or down.