basically the answer to all your questions is no.

In your case, it probably would be best to keep your Venice miles in CO's program.

You could then, next year, begin accumulating miles for yourself in WP since you will enjoy the benefits of CO Silver for domestic upgrades, boarding, check-in on CO, NW, or AS. I would probably enroll your wife and child in WorldPerks and count the miles to VCE in their new accounts, otherwise, you will have just more orphan miles in their Continental accounts. In your case, silver on CO gets you enough miles for a domestic reward ticket. The remainder will be orphaned and you will not benefit from the 50% bonus next year because you will be accumulating in NW's program.

Elite status is somewhat like fishing, once the hook is set it is tough to wriggle off.