I changed a few lines, added some links, increased the font size to bring it in line with my more recent posts and gave it a publishing date of today. There were no old comments yet, thus that all worked fine.

Done. Sometimes it feels good to act a little lazy.

Is there any way to set the post to have a new time so it goes up on a schedule in the morning?

You should be able to do that just like you would with a new post, and just use a future date/time for the date before you update the post.  Keep in mind though, that since it's already published, any traffic to that post between the time you change the date/time and when it goes live again will get a 404.  That includes search crawlers as well as any human visitors. 

An update on this from my world, I was inspired and worked out the permalink change from year/month/postname to just /postname. I used the Dean's Permalink plugin and tested it on smaller sites first to make sure it worked and I kept my traffic.

Now that it is done, I might dig through some of my older posts that had good potential, refresh the content, and bring them back to the front page. With an archive going back to 2008, I have lots of options.

I've noticed more than a few bloggers doing this.  The Redirection tool finds links on my site from carnivals and roundups, so the trend is noticeable.  I've been fixing the outgoing links.

I'm probably stuck with the year/month format having migrated from Blogger.

Now that it is done, I might dig through some of my older posts that had good potential, refresh the content, and bring them back to the front page. With an archive going back to 2008, I have lots of options.

Any ideas how to push the post to the RSS feed?

Hmm, that is unfortunate.  I'd really like to get some of our old (and favourite) articles to our new readers.  When we posted them originally we had maybe 25-50 subscribers and now around 700.  It would be great to have the articles "live" again.

I suggest that you either link back to them though new articles or you set them up in a different style and start a newsletter with your old stuff :-D

Growing a newsletter has made a huge difference in my traffic and income in 2011. For example, I don't solely depend on Google to drive traffic to my site. A single newsletter can bring an additional 200-300 visits in a day now ;-D

For those of you that do this, do you add a line into the post saying when it was originally posted?  Or do you just repost it and leave it at that?

I've done this just once on Bucksome Boomer and did add an introductory paragraph that did indicate the original publication date and why the post was being republished.  I have taken posts from BB and updated them for posting on my other blog.