[susan53]

Sorry, but your quote (where did you get it from? Always cite sources so they can be checked in context) just isn't true. Many function words - or grammatical words, like auxiliaries, prepositions, conjunctions etc - are monosyllabic words - eg are, can, to, for, and, but etc, and the question of whether they are stressed or not is entirely one of context. It's a matter of sentence stress, not word stress - which is what you indicate in your third paragraph.

For example, if they are at the end of an utterance they will be stressed, and a strong vowel will be used. The same if they are "cited" in an utterance, or carry emphatic or contrastive stress. In other positions they may be unstressed. Some examples :

David can(1)certainly be there. I'm not sure about Ellen, but I expect she can (2).
1 = /kən/ unstressed 2= /kæn/ stressed
A : What are you looking for (1)? / B : For (2)the scissors.
1 = /fɔ:/ stressed 2= /fə/ unstressed

So this means your questions are irrelevant. There's no need to look for a stressed syllable, because it's not necessary to have one for the schwa to occur.

As for questions of primary/secondary stress, secondary stress is only relevant to multisyllabic words. It's a feature of word stress - eg the word secondary has primary stress on /sek/ and secondary stress on /de/. As the word reached /ri:ʧt/is monosyllabic, it can only have one stress, which is by definition primary.

Can I suggest that your questions would be much easier to understand if you simplify them. Avoid background commentary, ask one question per post, and if you have others, include them in follow up posts after you've seen the reply. I think you'll find you get quicker and more satisfactory answers like that. At the moment it's very difficult to understand exactly what you mean, as so many things are jumbled up together.