For the second part, meta_query must be a nested array, like this
'meta_query' => array(
array(
'key' => 'cs_industry',
'value' => $relatedCat,
'compare' => 'LIKE',
)
),
for why it’s showing 5 instead of 3, this could be that your posts_per_page value is being overridden by a pre_get_posts filter, or something similar.