Where for a tube-newb to start?

If your question is what is the characteristic sound of particular brand/year tubes in each of these tube categories, there's lot's of anecotal info on the web if you simply run a search using the tube type. I have 'rolled' various tubes in different equipment over the years, and it is an enjoyable aspect of the hobby that can make a noticeable difference in sound.
Recognize that for any given tube, it may yield different results depending on how it is used in the circuit; thus, one person may 'like' a particular tube in a piece of gear that, to you, in your gear, may sound too euphonic.
Also worth noting that unless you are really knowledgeable, there is much confusing info about the old tubes- apparently, different companies shared manufacturing facilties, so a tube legitimately branded under a well-known name and place of origin may have actually been made for them by another company in another country. It is worth dealing with a legitimate supplier- there are several- if you are going to delve into 'new old stock' since the price of some old, highly sought after tubes is considerable and the potential for fakery is there.

Tand- I'm not sure, apart from old issues of the Tube Valley? magazine, maybe Glass Audio, mentioned above, that you'll find much in the way of scientific comparisons of tubes. There are tube data sheets for many tubes that are available for old tubes that compare specs. If you run a search for tube data sheets, you'll see what I mean, but other than electrical compatability, not sure those will tell you much about the sound.
What I was referring to was less of a commercial review, and more about user experience posting comparisons of different tubes in a given component (recognizing that different circuits may affect the outcome). I have posted such comments in various fora regarding comparisons of various rectifier tubes and my experience in rolling tubes in one of my phono stages. Garcia's reference to The Tube Store can also be supplemented by descriptions of various tubes on the Tubeworld website. I've bought a number of NOS tubes from him over the years. Good luck.

One of the challenges is to find new tubes that have the character of the grail vintage tubes. There is a thread elsewhere here on Audiogon about the rectifier the OP wants info on- and various comparisons among users who have tried different new tubes. For that tube, I am using a Mullard first series fat base, which is one of the grail tubes, but even these aren't the kind of crazy money that some tubes fetch. (And I have a stash of other old rectifiers for this slot, all of which sound different in my particular piece of gear).
Ultimately, a lot of people use tubes like tone controls, to flavor the sound to their liking, within a given piece of gear, within the context of a particular system and listening bias. The whole notion of tube rolling is, in some ways, experimentation (subject to using the proper tube that is a correct equivalent). Unfortunately, as TBG said, some of the most desirable old tubes fetch big money.

Brownsfan- you were one of the active participants in that thread I was referring to about the search for a new, readily available rectifier.