Lorelle, changing the sort order of posts is easier than pie with WordPress; just add this to end of the URL:
?order=ASC (or if a query already exists,
As for post numbering...Lorelle's suggestion is certainly easiest. WordPress assigns an ID number to each post but these are not reliable for use as post numbers since you can publish out of order, and deleting a post removes that ID from the records. There are ways to capture the number of actual post records, but tying row number to post would involve a bit of coding...
So how about if someone wrote a plugin?
Grab the zip, extract post-num.php from it, upload that file to your plugins directory, and activate Post Num under Plugins. To use, place:
<?php post_num(); ?>
in your template where you want to display the post number.