no
no (and besides, blockland doesn't run on source)
'reserved' is just placeholder text for a topic that the original poster ('OP') expects to be too large to fit into one post, and will be replaced with actual text once the first post overflows; that said, most people who reserve posts are getting ahead of themselves and are unlikely to ever even reach the character (IE: letters, numbers) limit on a single post
'OC' means 'original character', as in a fictional character that somebody took the time to make up, as opposed to lifting them from another existing piece of fiction for instance. the forum's general opinion of OCs (assuming i'm not out-of-date) is basically that they're all just self indulgent
milkshape 3d is what i use but i know for a fact most people use either blender or google sketchup