The only pool I've used that pays out the full amount of BTC is Swepool. Other pools like Deepbit will only pay out a portion.
For example, if you had 1.79658246 in your Slush balance, you would only receive 1.79 BTC. Only Swepool pays out the full amount so that your remaining balance is 0 BTC.
Because anyone using the default wallet will lose out on the change, as it doesn't take sub-cents.
Wrong. I have something with 6 or seven digits after the .