Here are a couple of links to previous discussions about this resort. Villa del Mar is the sister resort to the Villa del Palmar and you have full access to it.
http://www.puertovallarta.net/forum/viewtopic.php?t=7706&highlight=vi9lla+del+palmar
http://www.puertovallarta.net/forum/viewtopic.php?t=4395&highlight=villa+del+palmar
http://www.puertovallarta.net/forum/viewtopic.php?t=4379&highlight=palmar
http://www.puertovallarta.net/forum/viewtopic.php?t=4325&highlight=palmar
http://www.puertovallarta.net/forum/viewtopic.php?t=4291&highlight=palmar
If you use the search feature you will find a few more threads. Use Palmar as your keyword.
No need to rent a car.
Taxis are plentiful and the local buses are fun and cheap and stop right outside the resort. If you want to explore outside PV proper to the north then maybe rent a car for the day but beyond that you will not need one.
If you have anymore specific questions just ask.