Generally copper subject to heat cycles will turn an ugly dark brown through oxidation, so most copper heatsinks are nickel plated at the least. Also hides the solder joins and color mismatch between copper and aluminum.
Every vendor sells blower style cards, they are useful in some situations, particularly small form factors with few fans. The become part of the exhaust system. Also useful when you tightly pack multiple GPUs in the system.
Axial cooled cards generally perform better, and much quieter, but, yes add to the computer case internal heat. Requirement for them is good case airflow. Don't worry too much about the 'hot' air making a huge difference. That just sets the absolute floor your cooler can reach, as long as the air still has capacity to pick up additional heat other heatsinks will still be effective. The key is to get the warm air out of the chassis and fresh air constantly coming in.
Backplates are a bit controversial, and a lot depends on the design of the card. Some cards don't have that much on the backside to get warm, others have memory and VRMs. With larger cards they are really there for stiffness, a sagging card looks bad, and overtime through many heat cycles, may lead to premature failure. Components in a constant state of stress, getting heated, then cooled, something will give. Generally not before the card is obsolete, but any small defect in the card could be amplified in this manner. As above, don't worry too much about the heat coming off the back of the card, the fans will do far more to heat up the general area.
Not all gloom and doom though, it really depends on how much you spend what cooler quality you will get. Custom solutions from all the top brands should be decent enough.
- Custom (HOF, Kingpin, EVGA Classified, etc) (And hybrid water cooled cards as well, generally reference boards)
- Reference board with custom axial coolers (30 series reference designs are different from Founder's Edition this time around)
- Blower/Reference (30 series Nvidia Founder's Edition are axial/blow through coolers, 20 series were all axial)
These will be the ones that look 'all plastic' Actually just a vapor chamber and aluminum finstack usually (only copper base plus aluminum finstack for lower wattage parts)
You can also get pre-installed water block cards for full custom water cooling, they are basically economically identical to getting the water block of your choice. But then you need several hundred dollars in additional parts to make a water loop.