There are eight expansion packs;
University
Nightlife
Open for Business
Pets
Seasons
Bon Voyage
Freetime
Apartment Life
Chat with our AI personalities
If you are talking about installing a Sims 2 expansion to the Sims 1, it is impossible. You can only install the Sims 2 expansion packs into the Sims 2, not The Sims 1 or 3.
There are no mermaids in any of the Sims games or expansion packs.
Yes you have to have the actual game for the expansion packs to work.
No, sorry, the only expansion packs for the Sims 2 on PS2 is Sims 2 Castaway and Sims 2 Pets.
Yes you can. I have the Sims 2 Double Delux myself and I have all of the expansion packs installed and working on my PC.