1. Where are the previous versions of wordpress?
Answer: Go to wordpress.org. Then click on the red download button at right. In new page, look at left sidebar and click on Release Archive. Here's you are!

2. What is wordpress login url?
Answer: It is yourdomain.ext/wp-login.php

3. What is permalink and how to change permalink?
Answer: In Wordpress, the term permalink refers to url structure. The default permalink in wordpress is http://yourdomain.com/?p=123. To change this, login to Dashboard, go to Setting to Permalinks. Select your desired permalink structure and save.

4. How to enable file download in wordpress?
Answer: To enable downloads from your wordpress file, first upload those using Media to Add New. Copy the link location (File URL). This is the url to enable download of the uploaded file.

5. How to enable or disable comments on a page or post?
Answer: Login to wordpress. Go to all posts. Take your cursor on the desired post and click on the  Quick Edit appears below. Look at right and here's your answer.