Depending on the animals in your tank, 85F is usually not a problem, but it will cause a general increase in bio-activity on your tank. Also, O2 saturation is lower at higher temps, so make sure you're either using a skimmer or otherwise aerating your water well.

For kalk, there are a number of ways to dose effectively. The nice thing about KW as opposed to 2 part systems is that kalk does not add chloride ions to your tank, and it's high ph tends to neutralize acids that would otherwise deplete your carbonate ions (alkalinity). The theory about kalk helping with algae is that most nuisance algae supposedly prefer a lower ph.

Ultimately, most people that use kalk for their primary form of calcium and carbonate replenishment find that a kalk reactor, which is essentially a big cylinder that keeps the kalk stirred and out of contact with air, is the most convenient way to delivering it to your tank. As far as what KW puts into your tank, it's basically a balanced supply of calcium ions and carbonate ions, the latter through the reaction of hydroxide ions and carbon dioxide. (kalk is calcium hydroxide) One thing, potentially good and bad, is that the addition of kalk really cuts down on the carbon dioxide in your tank, which is needed for photosynthesis during the day. For this reason, many people tend to drip kalk at night, when all the animals are producing carbon dioxide. There's a lot of stuff written about this on the web; see if you can find some of Randy Holmes-Farley's articles.

In terms of supplying ALOT of calcium and carbonate to a tank with lots of fast growing SPS and clams, nothing beats a calcium reactor, which uses carbon dioxide to dissolve calcium carbonate in a cylinder to provide the tank with a constant drip of highly concentrated calcum and carbonate.