I recommend the following link as well:
Basic Concepts of Microsoft Word by Shauna Kelly

This is a part of paragraph formatting. It is the space set between paragraphs, specifically, space before the current paragraph.

Format > Style > Modify > Format (button) > Paragraph

I mean each choice except the last one. So, question style is followed by answer style which is followed by answer style.

For the last item in the list you choose the "answer last" style, which is set to be followed by the question style.

You apply the styles by selecting the text to which the style is to be applied and then picking it in the style drop-down menu. Ctrl+Shift+S
You can assign keyboard shortcuts to styles.

Had you started using the styles from the beginning it would be automatic. You are paying the price of that.
For use after-the fact, you do not need the last answer style. That one is used to make things more automatic.

This is a completely separate topic and does not have to do with styles.

The space for the text after a number is a part of the tab settings. Word inserts a tab after the number which advances to the next tab set. If the character is wider, that tab setting may be the one after the one that would be used for a narrower character. Increasing the font size will increase the width of characters but will not change the tab settings.

The tab settings should be set as a part of the Style. However, the Indent set after a number should be set in the numbering dialog, not in the style or paragraph dialog.

Keep in mind that Word has changed in part in response to problems people had. Thus Word 95 became Word 97 which became Word 2000 which became Word 2002 which became Word 2003 which became Word 2007 which became Word 2010 which became Word 2013 which became Word 2016. I do not recommend change for the sake of change. However, I would recommend that you try to get at least Word 2003 as soon as possible. It is significantly better than Word 97.

Woody Leonhard wrote an entire book about Word 97 called "Word 97 Annoyances." If you are going to stick with Word 97, I recommend it.