No, they will not be able to see or comment on your posts. If you add a comment to someone else's wall post, the person you have blocked will not be able to see your comment, which can make for quite confused reading!
When you expel somebody from your Page, they'll probably won't prefer it. This is a decent alternative for individuals you don't need after your Page's posts in their News Feeds or the News Feeds of their companions. Notwithstanding, Pages are open spaces, and individuals you've evacuated can decide to like your Page once mo