Adding additional Permalink to RSS feed

I’ve had feed problems like no other, and wondered if anyone could help me out:

1) My Facebook Page pulls the RSS feed for our “Featured” category, and I have my RSS set up to use excerpts only. So Facebook imports each new feature article as a “note” and displays the excerpt; so far, so good. However, I’d like for a “read more” link to appear after my excerpt. Without one, I have to trust that my Facebook fans will 1) know that this is only an excerpt and 2) find and click on the “view original post” to read the full article. For some reason, my excerpts NEVER have a read more appear after them, even on the homepage (not sure if my wp-smooth theme deliberately changed that). It was easy to hack in a “read more” link onto the homepage, but hacking it into the feed causes it to fail validation (Obviously the <a> tag I create isn’t defined in XML). Any ideas?

2) In the reverse, I have links that are posted to my Facebook Page automatically entered into my blog using the “FeedWordPress” plugin. However, anything pulled from Facebook always breaks by feed in the <guid> tag because of one of the custom fields that is pulled over. I just comment out the <guid> line in feed-rss2.php to fix it (probably not a good idea anyway) but then every time I upgrade WordPress, it overwrites my mod.

I know I’m in waaay over my head. 🙁 Any help would be hot.