The samplerate is the number of times per second that a sample of music is taken, so 44.1KHz is 44,100 samples/sec. The bitrate represents the depth of each sample, so 16bit means there are 65,536 possible values for every sample. Quantization is where the hardware (or software) has to pick between two values- what if the sample is between two of the 65,536 values? Then the quantization kicks in and moves that sample to the closest one. If you have a larger bitrate, less quantization will have to be performed, because you've got more possible values for the sample. Increasing the samplerate will give you more samples/second, which would be a more accurate representation for the sound.
So which samplerate and bitrate would i recommend? Probably 16/44.1 to be honest. You won't really be able to tell the difference unless you're recording classical music, (which has an enormous dynamic range compared to most other genres of music). And, as has been said, you've got to eventually downsample back to 16/44.1 for a CD, so if it's already in that format, there's no extra conversion needed. If it was in something else, you'd have to downsample, and thats more quantizing, which could cause loss.
If you're gonna change your samplerate, you'll have to keep it at that for the whole project... if you record one thing on 44.1, and another at 48, when you play them back, they will be at different pitches, and it's something that isn't the easiest to spot. So keep the samplerate consistent throughout, so that you don't have issues with playback