Skid plates will protect your drive train and cooling system and sliders will protect your sheet metal and are highly recommended.
Since you are new to off roading, I highly suggest that you go to DV with someone who is experienced with the trails and can provide help in the case of a breakdown or other problem. The sheer size of the park means help is a very long way off and very hard to reach due to very limited cell service. Many trails (ex: Lippincott Rd) are unaccessible to Tow Trucks and even if they could make it to you, it may cost more than you are able to pay.....
Trails that would be appropriate for you would be - Titus Canyon, Saline Valley road, West Side road, Warm Spring Canyon into Butte Valley Canyon and back out, Cottonwood Canyon and Marble Canyon (both dead ends) and Racetrack Road to Homestake dry camp and back to Ubehebe Crater. I would NOT recommend driving Lippincot Pass, Steel Pass, Echo Canyon or Mengel Pass without more experience and full armor.
There are gas stations located in Panamint Springs, Stovepipe Wells, Furnace Creek and the town of Beatty NV (near the entrance to Titus Canyon). If you fill up your tank at the last station before leaving pavement, you should be fine.
It is already getting very hot in DV. I try to get out there by late March while temps are still reasonable (low 90's) or after mid Oct to avoid the oppressive heat.
Sorry but I do not have any maps to share and the NPS map on the DV website seems to be down currently.
This website has some excellent information -
http://members.aceweb.com/oldtrailmaster/backroads.htm