Dear Scotland1960,
To answer all your questions accurately would take a book by itself...The Eight Tones is more than just a system of notes and scales. Although it is that, it is also a cycle of hymns. If you look at the Book of the Eight Tones (Octoechos in Greek or Obihod in Russian) you will find hundreds and hundreds of hymns devoted to each one of the tones, so that an entire service can be chanted (Matins or Vespers, etc.) with the prescribed texts for each tone. It may be hard to understand at first, but everything is cyclical, week by week, beginning at Pentecost.
The tones themselves roughly correspond to our scales, but the scale intervals, at least in Byzantine chant, can differ greatly from what our \"Western\" ears are used to.
I don\'t know if you are a musician, but here is a very rough guide to recognizing (and singing) the tones at least in their Byzantine form:
Tone 1: What the west calls the Dorian mode. It is the most ancient of the tones. It is just like our natural minor scale based on D or E.
Tone 2: What we usually hear the 1st and 2nd Antiphons in.. Many times it is like a minor scale but the drone or ison is on the 5th degree, like this--G-A flat-B natural-C-D-E flat-F-G--just like a C minor scale but the finalis is G.
Tone 3: Like our F or G major scale, but often has cadences on the 6th degree (Deceptive cadence in western terminology). Has a very joyful feel which is why some of the saddest texts are written in this mode as also mode 7, which is similar.
Tone 4 : Like a scale based on E using all the white keys of the piano. E-F-G-A-B-C-D-E. But if you ascend to the B and then immediately go back, the B becomes B flat.
Tone 5 (Also called First Plagal): Like our minor scale based on G or A. But in its sticheraric variant, it is like Tone 1 except when you ascend to the 6th degree of the scale and keep going up, the flat becomes a natural.
Tone 6 (Second Plagal). The most difficult to sing in, but the easiest to recognize. Think of the Greek song \"Misirlou\" or \"Havah Nagila\". There is a variant that sounds similar to Tone 2.
Tone 7 (Grave Tone): Like Tone 3 but with melodic line often starting on and revolving around the 4th degree of the scale. Sometimes can be hard to distinguish from Tone 3.
Tone 8 (4th Plagal): Just like our major scale on C, sometimes transposed to F or G. 7th degree flatted if ascending to it and immediately going down.
There are variants of all these:
Heirmologic--Fast tempo, usually only one or two notes per syllable, from the Heirmos, the first hymn of a canon.
Sticheraric--Medium fast, includes most of the Dismissal hymns and other hymns of the Liturgy
Papadic--so called because it imitates the way priests (papades) chant. The slowest of the three. Cherubic Hymn, Consecration Hymn, Communion Hymn in this style.
There are reasons why there are 8 tones, some of them are practical, some are theological (the 8th Day, etc.) but time would take me too long to elaborate.
This is just a very rough and undetailed explanation, I hope it piques your interest. A great source about our Orthodox Music, by my friends and colleauges Stan and Nancy Takis, can be found at
www.newbyz.org.