Sure, even without PM.
Tags generally work like this - [tag] text [/tag].
So, to answer your question:
To spoiler, insert "spoiler" instead of "tag".
To insert an image, insert "img" instead of "tag" and enter the link instead of text.
To cross out, insert instead of [tag].
Behold my horrible instructions.
Someone who knows a much easier way to do all that?