The entire point of an Add-Ons system is so that people dont have to conform to what the game was INTENDED to be, and can extend it and make it into whatever they want. So Im afraid I disagree with you on that one.
ALRIGHT, lets bee good people and stop derailing the topic...
What should I model? :D
Point 1, last thing, i find it look rather silly to see that togheter with the blockhead next to it.
I know add-ons are for user made content, stuff that isn't in-game yet, but that is really not in the same style as the original style of Blockland. :P
IMO, no support for Blockland but a good model nevertheless.
Point 2, i dunno! :C