Yes, maitl, ahuacatl, tetl, they are pronounced like that, but the TL is pronounced as well. Listen to the pronunciation of "ahuacatl" here: http://es.forvo.com/word/ahuacatl/#nah
It's the first link, by Benjamin.
"cempohualli ihuan chicoeyi tetl" is correct. In nahuatl, objects are seldom pluralized. You usually pluralize people, mainly.
"inic ce calmimilolli" is correct.
Yes, the H is silent in "Nahuatl", "Cihuatl", "Nahui".
Words with a "tzin" ending have the stress in the second to last syllable. "tlacA
tzin" for instance.