1. It makes a statement on their website about the ability to modify V1, they're not exactly discouraging it. Also, as Rashon said.
2. They were originally only meant to be for PC, the PS2 port was an attempt to boost sales, because not many own / owned a PSP.
3. Just like any other game, it will run on low settings, HL2, Oblivion, Fear, Assasin's... all designed to look great, but can be played perfectly fine on a lower end PC.