You're pretty much correct, but I thought I would extrude.
Spell Haste I and Spell Haste II have essentially the same effect, the only difference is the minimum casting time, and the level of spell it will affect. Spell Haste I affects only spells 20 and under, and only if they have a casting time greater than 1 second. Spell Haste II only affects spells level 44 and under and only if they have a casting time greater than 2 seconds. But otherwise, they both still reduce the spell's casting time by 15%.
If you have both, they won't reduce casting times by 15%, then another 15%. It will affect the spells if they fit in the catagories correctly. Like if your lvl 15 spell had a casting time of 1.5 and you only had Spell Haste II, it wouldn't work on it. I think this is because, in theory, new spells often take longer to cast as you get higher in level, so they restrict it to the higher level spells somewhat, but it would still affect the spell if it had a casting time greater than 2 seconds. What I'm getting at is not that it's only the higher-level effect works, it's that the spell needs to fit into the right catagory to work. So, say you had Spell Haste II already and a bunch of spells from level 20 and under that had casting times between 1 and 2 seconds, Spell Haste I would be actually worth adding, if you came across an item with it; not that it'll stack, but it'll overlap and affect the spells that aren't affected by Spell Haste II.
Now when it comes to specialized haste focus effects, the higher haste takes precidence. For example, Enhancement Haste cuts the cast time down by 30%, and the non-specialized Spell Haste reduces it by 15%. Your spells that fit in with the restrictions of both will only work with Enhancement Haste.
And as for Spell Haste, Mana Preservation, Extended Affliction, what have you, they affect different aspects of spell casting, so they will stack. Spell Haste reduces casting time, Mana Preservation reduces spell cost and Extended Affliction makes affliction-type spells (DoTs, snares, roots) last longer, so a spell will use each focus effect if the restrictions of each focus effect will fit with the spell you're casting.
I originally thought the same thing about Focus Effects; that the only difference was the range of spells they worked on (the I, II, III and IV) but I noticed that the minimum casting time is different for the different stages of focus effects.
Anyway, probably longer than this needed to be, but I'm tired and felt like rambling on, lol. Hope this helps someone :)
Edited, Sun Nov 24 07:44:26 2002

