The first part im kinda confused on, ("Now I went and found the problem of why my game wouldnt start. But now I need to get a new computer, but im just get the moniter and run the game off my tv.") The cars are models/skins that are replaced via Archive viewers such as Spark IV, Sound, Are sound mods, which are usually siren or gun sounds mods, replaced again through Archive viewers such as Spark IV, Lighting, I think your referring to ELS, ELS is a script (or asi, i think its actually asi, either or.) ELS is really simple to install, and for it to work you need ELS enabled vehicles (which you get by using like i said above, things like Spark IV and installing custom ELS enabled Cop cars) As far as changing a uniform, you usually are changing the texture, again, Through Spark IV, Just simply download the texture, import, Done.
Here are some links to help you:
http://www.gtapolicemods.com/ <for Custom Models/Textures of Vehicles in Gta, For other type of vehicles, Just do a simple google search, there are a ton of Modding sites which contain Vehcile Mods. (Gta4-mods, gta insides, etc.)
http://www.gtapolice...ds&showfile=198 <ELS For "lighting" on police vehicles, For this mod to work, you need ELS enabled vehicles installed, go to the site above to get some.
Again, Gtapolicemods.com have siren modifications, If your looking for "other" sound modifications such as gun sounds etc. Again, google search or simply gtapolicemods.com
And again, For custom uniforms, Gtapolicemods.com should have a ton
http://www.gtainside...at=326&id=28310 <Spark IV
<A tut. for Spark IV for both Steam and CD version Of gta.
Your post was a bit confusing, I hope my post helps you out, If it doesn't ill edit it a bit to help you, If you have any questions, ask me or anybody else on the forums, Im sure they'll be glad to help you.
Regards,
Justin, AKA, JAM.
EDIT: Here is another TUT: http://www.gtapolicemods.com/index.php?/topic/3373-how-to-install-weapons-peds-cars/