I want to buy a Raspberry Pi 3 Model B in a week, and I want to see if this SD card, a Sandisk Extreme 32 GB is good for the Pi? Also, I want to know if I can add an air cooling without heatsink?
That SD card is fine. I have a couple. They are actually kind of overkill, because the SD card reader on the Pi cannot read as fast as the card is rated.
add an air cooling without heatsink
This is probably not worthwhile. Think of it like your smartphone; I have never seen one with fans on. And your smartphone probably has more heat generating potential.
People do add fans to the Pi though, and there are other people around that will happily sell you a little 5V one if the Pi all by itself is too quiet for your tastes.
The Pi 3 is the only model with serious potential to overheat when not overclocked. You can tell by touching the SoC, if it is accessible; it should be noticeably warm but not uncomfortable for your skin.
You can also check with
vcgencmd measure_temp. Idling, it should be 40-45 C. When it is busy, it may get into the sixties. If you notice it getting to 75 C or more, try a heat sink before you bother with air. Air without heatsinks is not very effective at cooling small dense chips.