For fermenting, check the temperature range of the yeast you're using. Lalvin website lists ranges for their strains. I ferment my meads at the low end of their prefered range. Fermenting at too high temperature will give the mead fusels just like fermenting beer too warm. You'll get a faster fermentation at higher temps but to me the trade-off is worth it to go cooler. For long-term storage, pretty much the same principles as wine. Somewhere in the low 50s is ideal, I believe.