Think i knew that, though back when i played the campaign it wasn't with any mods and i never had an issue, though i did play with ECP but not with the campaign or any official scenarios, just scenarios i built in the editor.     Ya makes sense though, so basically as you said dont play the campaign with mods really, most especially ECP. Amazing how far the series has gone!

The script dynamically searches for all stored textures within the CfgVehicles. Essentially, for all vanilla vehicles (car, helicopter, plane), you should see all available textures as you would in the virtual garage. However, I haven't tested mod vehicles.   I also attempted to add some of the unused textures from BI using CfgVehicleTemplates, but it seems I am too stupid for that.

Well, here's your problem - whatever pirate website you got your illegal copy of OFP from, apparently doesn't have the Resistance campaign, despite claiming so. Arma Cold War Assault (which contains both CWC and Resistance campaigns) costs like 5 Euro on Steam, and I recommend getting it.

Does this work on any vehicle or only the ones that can be changed in virtual garage? 

That doesn't matter, OFP engine is limited to some crazy small amount of virtual memory (IIRC 2GB). When playing with big mods (and ECP is one of them - especially with all the bells and whistles turned on) it's easy to hit that barrier in just one mission - the more scripts run (ECP is heavy on scripts), the more units spawn, the more memory is used. Solution is simply "don't play campaign with ECP" (or at least limit your sessions to one mission - yep, even ending the mission will not free up all the memory used by it).   Having 666th gen Intel i69 with 77 cores and 88 jiggawatts of RAM doesn't change a thing - in fact sometimes game might not even properly detect the parameters of your PC, such as wrong CPU clock rate (oh, remember game sees single core anyway) or wrong RAM (for me it shows just 1GB of RAM out of 16 installed - doesn't matter when it comes to that virtual memory limit of 2GB though, since afterall it's a virtual memory, not physical memory limit).