Compression: is usually used to control dynamics but can be overly done and used as an effect. When using a compressor and you set a generous ratio, attack, and release you can lower the threshold until you hear the compressor squashing the sound and then at that very point you should push it back up to the point right before you hear the sound. Then apply a enough makeup gain to get your sound back. Thats a method alot of engineers use to gently control dynamics.
Limiter: can be generally used to boost the overall sound of a full mix to a prefered listening level (preferably near 0db), but sometimes can be used on individual elements such as vocal (for those singers who hit those Mariah Carey notes that damn near distort the hell out of your signal, etc.), and even drums. I know when you use software limiters and compressors its not really wise to overdo it because it can make a decent mix go terribly bad FAST!
Reverb: can be used in different ways. If you wanna get that "techno-like" distance sound then you can apply a nice amount of reverb with a fairly nice sized decay. If you want to imitate a small vocal room you will add just a little bit of reverb and a smaller decay. Once you start to hear to the reverb going on in the song, back off on the reverb just a little bit till you can just barely hear it... thats usually the effect most people go for.
HOPE THIS HELPS A LITTLE BIT, IM NO PRO ENGINEER BUT IM SURE THE GUYS HERE WILL HELP MUCH BETTER THAN ME. GOOD LUCK
