Learn Russian: Журналист переписал последний абзац и дописал статью. - The journalist rewrote the last paragraph and finished writing the article.

The base verb is писать (to write). Adding the prefix пере- usually adds the meaning of doing an action over again to fix or change it, similar to the English prefix re-. Therefore, переписать means to rewrite. Like most prefixed verbs, it is perfective, showing that the rewriting was successfully completed.

What is the exact difference between написал and дописал?

Both are perfective verbs indicating a completed action, but the prefix до- specifically means bringing an ongoing action to its final end point. While написал simply means wrote, дописал emphasizes that the journalist finished writing the remaining unfinished part of the article.

Why does последний абзац look like it is in the nominative case if it is the thing being rewritten?

It is actually in the accusative case because it is the direct object of the verb переписал. However, for masculine inanimate nouns like абзац (paragraph) and their matching adjectives like последний (last), the accusative form looks exactly identical to the dictionary (nominative) form.

Why did the ending of статья change to статью?