Don’t copy from Word. If you HAVE TO; paste the document into a plain text editor like Notepad, save and then re-open and copy/paste into your wordpress Post.
There is a difference c/p from a plain text editor as opposed to pasting from Microsoft Word. So, in essence, you can still c/p – just not from Word DIRECTLY into your wordpress.
As for excerpts, you can do this a number of ways.
Plugins
https://codex.www.ads-software.com/Plugins/Posts_Formatting.
https://codex.www.ads-software.com/Plugins/Posts_Miscellaneous
Or, if your theme accommodates it; you can have something like this:
<div class="entry">
<?php ($post->post_excerpt != "")? the_excerpt() : the_content(); ?>
<p class="info"><?php if ($post->post_excerpt != "") { ?><a href="<?php the_permalink() ?>" class="more">Continue Reading</a><?php } ?><?php comments_popup_link('Add comment', '1 Comment', '% Comments', 'commentlink', ''); ?>
Most themes have this option somewhere. Styling it is CSS driven.