Other Phonology Features
In Vinyar Tengwar, Volume 5b, Issue 48, pg 24, it is stated that "Khuzdûl, the tongue of the Dwarves, did not, however, tolerate two initial consonants." At the same time, Appendix F in The Return of the King describes the addition of Angerthas #35 as being " ' (the clear or glottal beginning of a word with an initial vowel that appeared in Khuzdul)". Both of these describe rules for syllable formation that are common, if not ubiquitous, in Semitic languages. Almost or all of them require syllables to start with a consonant. For words that seem, to native English speakers, to start with a vowel actually are beginning with a glottal stop. Many Semitic languages also require only one consonant to start a syllable, and those that appear to allow consonant clusters to start a syllable can sometimes be analyzed as having a very short schwa sound between them.
Beyond that, we know that Khuzdul can have two consonants at the end of a syllable, as seen in Khuzd and Sharbhund. That, apparently, is only at the end of a word, for in all other places where two consonant sounds occur, there would probably be a syllable division between them. This is due to the requirement of starting a syllable with one consonant. I highly doubt that there would be any more than two consonants to end a syllable, as I know of no Semitic languages that tolerate such, and it doesn't appear in Khuzdul at all.
Regarding what consonants may appear in cluster, it's hard to say what rules Khuzdul has. Some clues may be taken from what clusters do exist, the Angerthas, and assimilation rules in Adunaic. See the section below on Sound Changes for more information.
Not much can be said of assigning primary stress. Semitic language vary quite a bit, and Adunaic says nothing on the matter. The one thing we can say is that, for two-syllable words that have a short vowel in the first syllable and a long vowel in the second, stress probably falls on the second. This is because Tolkien envisioned a word salôn or sulûn "to descend, fall quickly" which would be borrowed into Sindarin and lose the first vowel to become slôn or slûn respectively. Vinyar Tengwar, Volume 5b, Issue 48, pg 24 It's more likely that the first syllable's vowel would be lost if it is unaccented. At least some varieties of Arabic also tend to favor syllables with long vowels for primary stress.