As, I mentioned previously : bottom left (this may depend on the style used)
hmm? that's correct and is can be confusing.
subscribeto topic/forum would leave no room for doubt.
This has been discussed many times and I am fairly sure that it is in the Bug Tracker
That would be construed as spam by many
You can send PM's to a group. If it's just specific members you want to send these multi PM's to you can create hidden group and add them.