Here is something i need to, but have not been able to find: how do you distinguish na'vi syllables? (i need to know this for infixes) 
Kaltxì Hippo!
In the dictionary, the IPA shows syllables as periods and infix positions as center dots. For example from the dictionary, for the word fewi:
fewi: ['f·E.w·i]
The syllable break is between the e and w. The infix positions are between the f and e, and w and i. The ' denotes the stressed syllable.
-Markì
Of all the words you could pick for an example, you picked a word that is at minimum irregular, or possibly is an error.
fewi: ['f·E.w·i]
Normally, /ew/ is a digraph representing a Na'vi dipthong. The first infix dot is in the right position for an ordinary word. However, a syllable break between /e/ and /w/ would be highly unusual. Especially when you consider you would pronounce this word as {FEW.i} (or possibly {few.I} at first blush. I know there are a couple of words where /ew/ is not a dipthong, and perhaps this is one of them. Is there any canonical source for this?
Ma HappyHippo77, in most cases the pre-first and first infix position is before the first vowel in the word (remembering that aw, ay, ew, ey, ll and rr are usually vowels as well), and second position infixes go before the second vowel. However, there are cases where the infixes go before later vowels, and these are usually compound words. After a while, the compound words get easy to spot. There are also verbs with just one vowel, and all infixes go before that vowel. Other than that, the infix positions are highly regular. When in doubt, the dictionary shows where they go.
A more typical word, and one used a lot for verb examples would be
taron, 'hunt' {"t·a.r·on}.
In general, the rules for Na'vi syllabification are simple and easy to learn. A syllable consists of a vowel, which can optionally have 1 or (in some cases) 2 consonants before it, and optionally a consonant after it. The principle of
maximum onset is generally followed, which means that the consonants generally go before the vowel when there is a choice. It is all clearly explained in
Horen the reference grammar, in section 2.1.4.