latta (sg.) = latte (pl.) and latte (sg.) = latti (pl.)
You bring up a good point!
I think the difference between latte (cans) and latte (milk) is solely contextual. Just like some homophones in English. (Except in English, we're less likely to call them homophones and more likely to call them different definitions of the same word, the same series of letters.)
Yes, it has no plural. Remember that in the major part of the cases uncountable nouns in English are uncountable also in Italian (they area part of the nouns called difettivi because the plural(in their case) or the singular misses: difettare (1st coniugation) means to miss). So, for example: The water misses the plural, and it is the same in Italian, except for some semantic areas, which are the same in English. Hoping to be clear.
Typically any "a" in Italian is pronounced as it is in the English word "father". I say typically because regional dialects can vary slightly in pronunciations, but any Italian would understand you if you pronounce it this way.
A nice thing about Italian is that it is phonetic--words are spelled exactly how they are said. The catch is that every word has a syllable emphasized and you can't necessarily tell this from the spelling. More often than not, this is the second-to-last syllable.
Taken by an Italian grammar book: that is a table about the plural of the major part of names and exceptions, but there are orher exceptions which you have to learn by heart: PLURAL OF -A NOUNS: 1) a)masculine pl. is in -i b)feminine pl. is in -e 2) names in -ca and -ga: -chi or -ghi 3) names in -cìa and -gìa: -cìe or -gìe 4) names in -cia and -gia:-cie or -gie. PLURAL OF -O NOUNS: 1)regular names: -i 2)ending in -co and -go: a)chi or ghi if the noun's accent is on the penultimate syllable b)ci or gi if the noun's accent is on other syllables 3)ending in logo: a)-logi if it is a name which indicates a person b) -loghi if the name indicates a thing 4)ending in -ìo: ìi (the accent is on the penultimate letter) 5)ending in - io: i (the accent isn't in the last syllable) PLURAL OF -E NOUNS: 1) regular nouns: -i 2)ending in -ie: -ie : la specie le specie (the meaning is the species Remember that there are some ecceptions, I have already said it, and you can see some of these nouns here on Duo, but you can search other nouns on the Web. I hope I have been clear.