Michael Stieman and I are already working on an events module (as you mentioned), and will hopefully release it very soon. We are not initially releasing the pricing functionality, but it is in the data model (much of which was carried over from the openacs 3.x module), so that wouldn't be a hard addition. regarding your points
1) our module will have the ability to allow users to add venues - all you need to do is give them permission to do so.
2, 3, 4, 5) none of this is accounted for - though integrating with survey will likely help in providing this functionality (this integration is already in the works). Having survey provide service contracts will be happening in the next months...
6) i don't know anything about this.
The changes/additions you want are very substantial... so i'm not sure if you would like to base it on our module or not... but once it is release you are free to do so...
