As Artmaltman indicated, Robert Harley's book would be one good resource. For even better, more up-to-date information on specific products I'd suggest you do your research right here and on Audioasylum. All advice should be taken with a grain of salt, of course, as this is (arguably) such a subjective hobby, and is chock full of folks who seem to think otherwise. Also, system/component synergy can make or break any purchase. Still, ask your questions here, search the archives (first) for answers, and I think you will be pleasantly surprised at how responsive folks will be. As you've already found with the reviews in the Audio rags, they are overwhelmingly positive, and often skewed by the fact that the advertisers are supporting the magazines. Read as much as you can, and more important, try to get out and listen with your own ears and make your own judgements. You may find that your opinions differ from the 'experts'.
Regarding your questions about universal players; some do indeed do a darn good job with all formats, though most reviews I've read indicate that the better dedicated units will still outperform in redbook (standard CD format) playback. You can read plenty of opinions here and on the Asylum as to the other formats and how they sound. I think the factor that has kept me sticking to redbook has been the lack of availability of a wide range of titles in either 'alternative' format. Right now they seem to be audiophile novelties and who knows if the recording industry will ever truly embrace either. Until then I'd rather put my money elsewhere, but that is just me of course. I'm not familiar with your front-end gear, but I'd bet if they are 15 years old you'd get a big bang for the buck in replacing your DAC/player combo.
As far as further advice, you may do well by stating some of your own listening preferences as systems may be put together to suit those.
Above all, enjoy the music!
Marco