You bet. Your 24-bit and 16-bit tunes are welcome, and lossless file downloads in FLAC, WAV, and AIFF will always have the same bit-depth and sample rate as the originals you upload. If you plan on uploading a file with a higher sample rate, be sure to leave at least 0.5 dB of headroom to avoid undesirable clipping in the final transcoded formats.
For ALAC, larger sample rates will be reduced to 48 kHz.
The bit-depth and sample rate of lossy downloads (MP3, Ogg, AAC) are determined by the different devices your fans use for playback, but whenever possible we use the higher-quality option to generate those files.
We have no plans to support 32-bit files at this time.