How do Terminators use their energy or get it from other sources, and how do they process food waste?
Terminators, of course, have their own power source – a nuclear power cell with about 120 years' worth of power on average levels of usage – but they can get outside energy from heat and food. Dedicated heat sinks exist to absorb and use energy from warm sources. For food, Terminators don't need to eat – they may do so to infiltrate better – as their intricate systems recycle and reuse energy to keep up the modified body and tissue, edited such that actual nutrients aren't necessary. Terminators' systems are so intricate and efficient that they quite literally use up all energy when food or drink is consumed. Waste and byproducts are converted into other forms of energy, such as sweat, heat, or the like, and emitted that way. The stomach and intestines of humans are like holding areas and converters in Terminators. "Synthesize the chemicals, break down the compounds – done in full, no matter the nutrients, by a miniature, mechanized “digestive” system performing a series of revolutionary and sophisticated bio-engineered processes that wastes no resource – convert it to heat, stored in interior sinks. The system is hyperadvanced – nothing will be left."
This is addressed in 000.
How much variation is there between models' individual units?
As we know, there are ten of a kind for each model – so ten model 100s, ten model 101s, and so on. Within each "batch," though, there is indeed variation – though they are near-identical but for those few things. "Each individual has its own discrepancies, none of these rendering them unfit for use or imperfect in design. In fact, minor exterior deviations are a feature, not a flaw." Their DNA is the same, but skin features (such as freckles or texture), physical age, dental patterns (because the teeth are taken from formerly-living humans and are not manufactured), hairstyle, body hair pattern, height, muscle build, and such shift from unit to unit. It might be helpful to think of them as identical twins, just that there are ten of a kind, not two. Same DNA, practically the same outcome, but for a few things.
This is addressed in Butterfly.
Can Terminators reproduce?
The 600 series did not have proper human components – it had human hair and teeth, but its skin was made of rubber, and it was intended for battle-based infiltration as opposed to more nuanced and “human” contexts and situations of infiltration. The 800 series, designed for far more believability, had living tissue and other bodily components made of modified human DNA in addition to human skin and hair, and it was made to accomplish far more infiltration tasks and related tactics, including of a sexual nature. Those units fashioned with living tissue and its ancillaries thus contain the “ingredients” necessary to is copulate, and they do have a sort of genetic sequence that grows and maintains hair, skin, musculature, of a model’s design. This also allows the creation and circulation of modified cells of several kinds. Outfitted units do generate semen. Presumably, Skynet would not have gone through the efforts to delete sperm generation from its modified genome sequencing and development, as it would be a waste of effort. Therefore, it’s unknown whether outfitted units generate sperm and whether they can successfully reproduce. Female units are equipped with appropriate anatomical adjustments when living tissue is applied, but they lack the proper organs to reproduce. Male and female units outfitted with tissue have prosthetics applied for proper and believable anatomy, which do function as in humans. The abilities of the 1000 series remain largely unknown.