If you want to know the post count number of a post, click the time stamp in the top right corner. It will tell you the post count number. You can also find the post count number by looking at the url when you link it. The post count number is the number at the end before your username.
On starting new topics.
Discourse gives several options to start new topics. One is just to click the + new topic icon at the top right of the board when you’re at the menu screen.
Another is to click the arrow next to the person/thread you’re replying to in the editor box.
Another option to start a new topic is to click the new topic button when you’re looking at the person’s post number by clicking on the time stamp in the top right corner of the post.
[For the mods.] Slow mode and timed closure. Slow mode stops sequential posting over a certain number in contentious threads. Timed closure allows the mod to close the thread for a specified time and open at another specified time.