Hi Gregathon.
Yes, naval units can be placed in a hostile SZ, as the Combat around is over.
It is up to the other power to either initiate combat or move away in his next turn.
A Transport can only load up to two units and its turn ends when it offloads them or when it has moved two SZs(units still onboard). It can pick up units anywhere along its two movement path(as long as the SZ is friendly), including at the end of two, but its go ends when it drops them off. This means a Transport might not move at all, as the units to be dropped off are in the territory adjacent to the SZ in which it begins its turn.
It cannot pick up 4, therefore.
Hope that helps you. Please ask again if unsure.