Add “Read more…” with link to original article, etc.

1) Some of my RSS Feeds come with "Read more..." message alongside with a link to the original article, but most RSS Feeds don't. How can I force adding a "Read more..." message (and customize/translate its text) with a link to the original article? 2) I'd like to shorten the displayed text in a post not by number of characters (which hasn't worked properly in some of my tests), but rather by number of paragraphs (or alternatively, "full text minus n paragraphs"). Is there such a possibility? Best regards, Peter