Yes. When a Sim dies you still have the BG options of Played or Free Roaming (unplayed) Ghost. You just have the additional option to Rebirth on death (if you have earned it before death, else it's greyed out). To have them haunt your house like before, just keep the grave marker (urn/tombstone) on the lot and there's a chance they'll spawn at night. There's also the Spooky Lot Challenge (CL) that will spawn random Ghosts for you.
If you have Seasons and craft any Flower Arrangement scented with Death Flower you can gift it to any Sim to age them up. If you gift it to an Elder, they will age up to... Dead. I'm not sure if there's an option for pets. Might be possible via an Age-Up Treat on an Elder pet?