For sounds, try Freesound.org or Sweetsoundeffects.com, or even try recording your own.
Second, what mic do you have? Does it have different recording settings?
Try recording a voice line using Audacity, then leave a few seconds on the end for just the noise. Then try the noise removal tool.

Fancypants has a tutorial on noise removal, which is a really good thing to watch.

When you do record voices or sounds, make sure that as little background noise is around you as possible, and preferably use a more silent computer.  Turn off and fans or anything that could add to the fuzz.
Even if you take away everything you can, though, there will still be some fuzz, but that can be removed.

I prefer to only use sound effects I've recorded myself in my own brickfilms, so I've gotting pretty good at making sounds.  I find a useful thing to do is to use the sound of LEGO rather than more realistic sound effects whenever it's possible.  Since everything is made out of plastic is actually makes sense, though.

My preferred footstep sound is made by actually making a mini-figure step on a stud as so in the film it will sound like a LEGO person is walking on actual plastic.  A great advantage to this approach is that a single set of footstep sound effects can be used for any situation, whereas using more realistic sound effects will make you have to get sounds fer several different situations such as a grass footstep, a wood footstep, a tile footstep, and so on.  Also on harder surfaces footsteps change very much depending upon when sort of shoes the individual is wearing.