The reason why you see odd numbers for haste items is because in order for the haste to work, you have to be one level before the said haste percentage.
For example, if the Catfur Sash has 11% haste, you have to be level 10 in order for haste to kick in. For 21% on Ornate Girdle from Veksar, you have to be level 20, etc., etc.
I played a monk exclusively on live, and knowing all of this was second nature.
Also, the max haste is only taken into account with the higher haste item percentage. If you have both of the above haste items equipped, then you will only get benefit from the Girdle - but not until level 20. That's why you should wear the haste item you get the benefits from according to your level.
Bard haste songs and spells (shaman, enchanter) will overwrite each other depending on which is faster. So if you're bard is weaving Jonthan's Provocation (50% @ max level) and the enchanter is buffing you with Swift Like the Wind (60%), then there's really no point in the bard hasting. Have him twist a different song. I can't tell you how many times I've had to explain this to people I've grouped with.
Except for the Monk epic (which is essentially a bard song) and disciplines, none of the above will stack with any other class. That's why playing a Monk kicked much, much ass. Can't beat the 95% haste with combined items/epic/disc and spells.
