Arabic linguistic terms problem

Dear friends,

as you know, I'm designing an Arabo-Romance conlang "Ajami". Its description
ought to follow Arabic linguistic tradition. Due to this fact, I've met some
problems while composing Ajami grammar description. I'd appreciate if
somebody can give clarifications with respect to the following issues:

The term "Harf" is very ambiguous. It may denote 'letter/character', 'sound'
or 'particle'. The latter class includes prepositions, conjunctions, proper
particles, articles and some other kinds of auxiliary words. Shall I follow
this practice, or find/invent some alternatives?

The term "jam3" traditionally is translated as 'plural'. Farsi uses it in
this sense too. But in Arabic it means rather 'collective noun' that implies
plurality. Ajami has both regular Romance plural and collective forms
borrowed from Arabic which Arabic grammar ususally calls "jam3 mukassar"
(broken plural). The latter may form regular plural too, and demands the
verb and the adjective to agree with it in singular (!) form. An Ajami
example: darso 'lesson' ~ darsos 'several lessons' ~ doruso 'classes',
'course' ~ dorusos 'courses'. Shall I still call the form like darsos
"jam3o"?

Is it OK to classify interrogative adverbs (when? how? etc.) as pronouns?
What is the difference between "qayd" and "Zarf"? Does the latter means
"adverbial modifier" (sentence member) rather than "adverb" (part of
speech)? Or is this difference know exclusively to European school, and
escapes from the Near Eastern point of view?

muHtaraman,
-- Yitzik