As suggested by the others in this thread, I would check motherboard compatibility lists for the sticks (or just 8 GB ones in general, if your preferred model isn't there). Googling your planned component combination is another way to explore compatibility, as you've already done.
Motherboard and RAM stick compatibility is still an issue today, and it's an annoying, sneaky one. Loading all 4 slots I don't think is wise, it puts more power strain on the motherboard, and previous controllers at least have indeed had stability issues with 4 vs 2 sticks. Unless we're talking heavy overclocking, the speeds aren't massively important (CL9/1600 is typical for 4 GB), but at low performance levels it might be the last straw. As Vicotnik pointed out, there are options, so I don't think you should settle for CL10 or sub-1600 speeds (check review sites like X-Bit Labs or Techpowerup for analysis).
As regards to heat production: if the maximum operating power of a component is 2-3 W (check specs, e.g. http://www.kingston.com/datasheets/KHX1 ... 3B1_8G.pdf
), it's very unlikely it'll influence a standard or even low-airflow system's heat balance or overheat itself.
The main question about low-voltage sticks I would think is "why not"? It obviously takes a higher grade of components and/or design to be able to operate at lower voltages, and throwing in extra voltage without overclocking is just pointless waste. So: why would you NOT want a low-voltage stick? A 20% price premium might be steep in principle, but if we're talking $25 vs $30... I would pay the $5 for better components (and thus an improved world, if you're a tech-hippie(?) like me).
PS. My personal favourite is G.Skill RAM, found good specs and recognised design for decent prices. Below is a price comparison from today.