CEP uses 32bit float to open/record 24 bit files. You can save as 32bf or 24 bit (using dither). Altenately, you can work everything in 32 bit, save as 32 bit and use another program to dither down (I like working in CEP but use the UV22HR in Wavelab to dither down to 16 bit for making cds).
I don't think that s/pdif standard supports 24/96 (not sure about this one). Use the USB into your pc, then select the UA-5 as the input device in CEP. That should open up your sampling rate/bit depth options to 24/96.
CDWave will also work fine - again, use the USB, select the UA-5 as your input device.
After doing a recording, run the CEP analysis on a small section and it will give you the true bit depth. Just because you're recording in 24 or 32fp doesn't mean your feeding it that level of detail. Wavelab also has a 'bit meter' that does the same thing - tells you the actual bit depth of your signal.