Can people still see my post when I don't have the same hopscotch version as them?
Yes don't worry, your posts are still there.
I checked your profile and the last project you posted was 20 minutes ago so you shout be good.
Yes they can. But you can't see projects from the new update. Why can't you update? If there is a problem I would make a project and write your note on it and ask people to report it so the hopscotch team will see it rather than it glaring in the distance. Or write an email to them.
Long story short, it is a school ipad, that is why I can't update.