2) Spam is against the rules here. Major offenders will be temporarily banned. If you don't have something useful to say, then don't post it at all. Double posting is prevented for the most part due to a forum-wide software limitation on them. Groups are also seen as spam if created OUTSIDE the Groups sub-form.
This also applies to bumping, which is when you post in an old thread in order to bump it back to the top of the most recent threads to give it more attention. This is only really allowed if your bumping post has something relevant to the topic, or a serious question is left unanswered in a help thread. Otherwise it is considered necroposting. https://powdertoy.co.uk/Discussions/Thread/View.html?Thread=543