Anyone know a php snippet for showing the first 200 characters of the most recent post?

WordPress has an inbuilt function called the_excerpt() which echoes an excerpt of the post content.

By default an excerpt is 55 characters. You can set it to 200 like so:

function your_excerpt_length( $length ) {
    return 200;
}
add_filter( 'excerpt_length', 'your_excerpt_length' );

This should go into your theme’s functions.php, ideally.

EDIT: To manipulate the excerpt more string, use the following:

function your_excerpt_more($more) {
    return '';
}
add_filter('excerpt_more', 'your_excerpt_more');

Given that you commented that the_excerpt() does not output the native […], it is likely your theme already makes use of that filter somewhere else to replace the normal output with the described “… Continue reading →” link. So rather than adding it again, find that in your theme.