GaryKiller15

Nice to meet you,Mr. GaryKiller15 and welcome to the site.We hope you enjoy your stay here.
LCPD:FR installs any ASI loader (any one of the existing two) at your will,during initial installation steps.Though,LCPD:FR is just a modification itself,so it would not be appropriate to say that it runs other mods.It just gives an ASI loader to your directory through which other mods (and the LCPD:FR itself)runs.
Patches,are,as usual to improve the gameplay and fix the bugs in game,officially released through the parent Developer company,in this case Rockstar North.As for running the mod,you need 1070 patch to run the latest 0.95 RC2R2 installation of LCPD:FR.
You might/might'nt need a trainer,necessarily.Trainer is just a simpler form of cheatcodes.Here,I'm assuming that you have a basic knowledge of games being a hardcore gamer and you know what cheats are.
Although,I'll recommend installing a PDF reader and strongly recommending installing WinRAR (a program to open rar files,exactly).
You'll find the guidelines regarding every mod upon opening the winrar archive of every mod,so try and read them as much as possible.
As for drag and drop and copy thingy,I hope you'll learn that only by playing around with things since every man understands those basics on their own.
The only solution to get yourself outta this trouble is just keep reading and trying.Its not that hard,believe me.Wishing you good luck.

Best,
Dhruv

You've posted this in the wrong section, I've moved it to GTA IV > support for you.

Furthermore, you can find the answers by researching a bit, both on this site, and by Googeling.