1. The number of posts drops off over time. After submitting roughly 50 posts, bitcointalk is counting 32 of them. I do not make spammy or irrelevant posts and they are not off-topic.
Posts do not "drop off over time". Your posts were
deleted for being spammy, irrelevant, or off-topic, and you are likely to be banned if you continue making such posts.
They don't drop, it is just that sometimes they don't appear on the post count. Even if they are not deleted nor classified as spam.