I'm really not the one to be giving technical information, but I'll give it a try here, and hope that someone with better information can correct me:
1. Redbook CD is the regular CD you buy at the store. I believe that the players you mentioned above are regular redbook CD players. A redbook CD has 16 bits of information sampled at 44.1 Khz stored on it. A redbook player with "upsampling" capability can add digital noise to come up with a 24 bit/96 or possibly 192 khz signal to be processed, but it really can't add any information to the CD's information (although I do think a properly implemented upsampler such as the dCS Purcell can make a CD SOUND better). But a CD player without upsampling capability will only give you a 16 bit/44.1khz signal from a CD. There may be a reason that a true 24-bit DAC might be better at decoding a regular CD than a 16-bit DAC, but I'm not aware of it.
2. SACD does not sample at 192khz, it's some ridiculously high number. You need an SACD player or a universal player to play the SACD layer of an SACD. I don't think either of the units you mentioned can read and play back the SACD layer of an SACD.
3. DVD-A is (and I'm generalizing and ignoring the various multichannel and other capabilities here) a pcm-based 24 bit/96 khz medium, which requires a DVD-A player or universal player to decode at this time (I think some DVD players can play them too, but I don't know if they can fully decode the 24/96 signal). There is also another 24/96 medium out there, the DAD (principally available from Classic Records and Chesky), which is DVD-video based and likely to be left by the wayside in the high-rez wars, can play on a regular DVD player (not a CD player, though) and can, if your DVD player has a digital output that can output a 24 bit/96khz signal, be played through an external DAC with 24/96 capability. I think, and someone please correct me, that DVD-A still has an encryption scheme in the software that prevents a 24/96 digital signal from being passed from a DVD-A player, so you can't currently use an external DAC to play a DVD-A disc.
4. HDCD is a 16 bit/44.1khz medium, with some special encrypted signal or something manipulation that does make a sonic difference from the standard redbook layer but requires a decoder in your CD player to reap all its benefits.
This is really basic, and pretty confusing. Bottom line is that if you buy a redbook CD player, you won't be able to play anything other than CDs in it; if it has 24 bit DACs in it and 96khz sampling capability, it can possibly sound better than a standard CD player, but you should check the archives under "upsampling" to get an idea of the controversy around that process.
