2001 Pathfinder alarm Search

Hi, Can anyone tell me if the 2001 Pathfinder SE comes with a factory alarm installed and if so where is it located. I know it has the factory door lock/unlock that I use the remote for, but I seem to recall sometime back that it had an alarm also. If it does, how do I program it to use the originl remote. If by any chance it doesnt, I have a Viper550esp that I want to put in. Can I still use the factory remote or do I use the Viper's. I dont want to use 2 remotes. Also any special notes I need to be aware of for the intstall: such as more than one door unlock wire or any troggers I need to be looking out for? This is my first pathfinder install. Do I interface at the SECU module and just use diodes? All input would be greatly appreciated.