It's a spanish word that means "bite size food", they're appetizers that are a staple of Spanish cuisine.
And yeah, you pronounce it tah-pass, there is a song called Vamonos de tapas, you can listen to it to see how spanish pronounce it, latin american peeps may pronounce it differently tho =] .
You can also type in google translate the word tapas under the spanish language and click the speaker icon to listen to more likely how it sounds.
Finally, yes the name tapastic comes from that spanish word.
