We can start on any lot/house we want. But we cannot move houses, just worlds, and only once the requirements are fulfilled.
Correct, you can start on any lot/house you want. Moving world only when requirements are met. As for moving houses, the team needs to discuss this matter further.
The military sim must go to work all days, so no calling in sick and/or taking unpaid time off
Correct.
No premium content, since it usually provides an advantage. Does this also apply specifically to the changing station that we got with the lullaby set?
No premium content at all for tournaments. The changing station lullaby set cost 1900 simpoints at the store, so the item will not be allowed for tournaments, sorry. Anything that requires you to pay simpoints (money) to purchase cannot be used for these tournaments.
Kids can do pretty much whatever they want. Except move a partner/spouse in, and daughters can't have nooboos (but sons can, since they aren't born in the household).
Remember, tournaments are on "long" lifespan. Your starting Sims, their children and any pets are the only household members allowed, so this means the children of your 2 starting sims cannot have any children of their own or move in anybody.
Metro / Black might still make changes to this though, so keep checking
