A couple things--first, the discussion of modes is pointless and meaningless unless you are talking about a specific sort of music--Jack Campin's articles are very useful because they have a very specific subject, and are replete with examples--

Second, the Diana Stork businesss referred to above has to do with the plagal modes that Foolestroupe made the comment about above--the original eight Church Modes consisted of four authentic modes, Dorian, Phrygian, Lydian and Mixolydian, in which were descending octaves that ended on the name pitch, and plagal modes, Hypodorian, Hypophrygian, Hypolydian, and Hypomixolydian, which went a fifth above and a fourth below the name pitch.

third, to make things less confusing, it is helpful to think of their being two different classes of modes, relative modes, in which a C dorian mode would be a Dorian that starts on D relative to C, and absolute modes, in which the C dorian would be a dorian that starts on C.

Fourth, "tempered" means that all the half-steps in the scale have been evened out. There are various systems of temperament for keyboard instruments and fretted instruments, however, many instruments, such as violins and trombones, are not tempered--that means that notes like F# and Gb are not the same on them, and that, when playing in the key of C, C to G is a perfect fifth interval but D to A isn't, and the reverse is true in key of D--

Fifth, for practical purposes, Ionic, Dorian, Phrygian, Lydian, Mixolydian, Aeolian, and Locrian relative modes all have the same notes in them.    This means that when you play one, it is pretty much going to sound like all the others, unless you have further rules about where you start and end--