I'd look at the wiki page for biomes
http://dwarffortresswiki.org/index.php/DF2014:Biome.
Savagery: Non high savagery means only "normal" creatures are available (no giant or animal versions). Also Highwood exists only on savage embarks, and I think it's whip vine that's also savagery dependent. In addition to that, high savagery allows two groups of critters to be present on the same "level" (surface/each cavern) at the same time, while the normal case is one. High savagery also prevents civs from settling/spreading. As far as I know, savagery is the only feature that change with time, as civs can degrade the savagery of nearby tiles to eventually be able to settle on them (so a nice savage embark scouted out at year 1 might have lost the savagery by year 1000 when the world is regenerated with the same seeds).
Evilness: Yes. The only ones who can start in evil terrain are goblins, for instance. Humans and dorfs require neutral. Note that this is for the civs, not your embark. Also affects what creatures you can get (with reanimation and various freakish weathers in evil biomes).
Elevation: A messy term as it's used both for gradient and altitude and there is one tab view for each of them. DF makes use of two elevation systems, just to mess things up.
PSV wise 300+ is mountain, 100-299 is normal, 1-99 is ocean. Post world gen the ranges are compressed. 1-99 is still ocean, 100-149 is normal, and 150-300 is mountain. Hills are actually controlled by drainage and causes plains to split into normal and hilly ones. I look at the biome rather than absolute elevation one embark (but I want it absolutely flat), although I think a high embark usually results in a longer distance down to the magma sea.
Temperature is messy as well. I generally look at biomes again. If you don't have poles in your world < 85 is "temperate" and 85+ is "tropical" while biomes in worlds with poles are controlled by latitude (allowing you to have freezing cold tropics...).
Taiga is <5 degree forest, while tundra is the same non forested biome. Glaciers should obviously be freezing...
I avoid anything that risks freezing during any part of the year because you can't stop the morons from getting killed by freezing/thawing (you can reduce the risk a little for your citizens with traffic restrictions, but caravans, invaders, and visitors ignore them completely).
Rain: Affect the biome, and that's what you really want, so ignore rainfall and look for biome. Rainfall < 5 causes trees to not regrow, while <3 does the same to shrubs, and 0-1 is completely devoid of greenery (but channeling down into the soil grass will still grow there).
Drainage affects the biome and hill/flat for grasslands. Also affects aquifer probability. Again, you're after biomes unless you're building a PSV world.
Aquifers cover complete biomes, so if the embark has several, some of them may have aquifers and some of them not. Adjacent biomes with aquifers do not have to have them at the same level.
River/stream/brook is covered by river, and the embark info shows what the feature is.
Single/multiple: Should be exactly one vs more than one. Again, it's per biome.
I'm not sure what the various soil depths are. However, I like to have my underground farming in soil but not directly below the surface (due to tree holes in the roof). A deep soil together with an aquifer can mean you get several levels of aquifers in soil (which are more painful to deal with than stone).
World creation: If you really want to control what you get you should go the PSV route and design the world. That way you can design is such that the goblins, human, and elves are separated until you embark at an "ocean" tile that suddenly connect everyone to you. Few titans and megabeasts means they won't trash as many settlements, short history means goblins (usually) won't get to steamroll everyone else. Using Legends Mode to look at the viability of various civs/races before embark is also useful to find out whether to actually use that world or generate a new one (I export the XML data and look at it with Legends Viewer).