It's generally assumed that you can't stick material of arbitrary length and near-abitrary content into the middle of a word. As mentioned in Yellow Sky's comment, we can say, in addition to "an apple", "a yellow apple", "a lovely, delicious yellow apple", and so on.

"Of" is not analyzed as a head-marked possessive suffix for a various reasons. There are many contexts where "of" phrases are used where "of" is not directly after the head of a possessive construction. "Of..." can be used predicatively or used in coordination ("the well-being of the people and of the government").

There are some real cases where it's unclear whether to analyze something as one word, but I don't think any of the examples you gave are of this kind.

Some examples I know of that have actually been considered to cause some difficulty for analysis:French verbs and the prefixed pronouns (especially the non-subject pronouns, but to an extent even the subject pronouns); French prepositions before proper nouns (like country names); English compound nouns of the form adjective + noun that are written closed (like "blackbird") vs English adjective + noun sequences that are written open, but stressed on the first element (I can't think of an example right now--I'll add one when I add the citation).

It's generally assumed that you can't stick material of arbitrary length and near-abitrary content into the middle of a word. As mentioned in Yellow Sky's comment, we can say, in addition to "an apple", "a yellow apple", "a lovely, delicious yellow apple", and so on.

"Of" is not analyzed as a head-marked possessive suffix for a various reasons. There are many contexts where "of" phrases are used where "of" is not directly after the head of a possessive construction. "Of..." can be used predicatively or used in coordination ("the well-being of the people and of the government"). Also, you can put a conversational aside before "of", like "the perception--which I think is false--of X as Y...".

There are some real cases where it's unclear whether to analyze something as one word, but I don't think any of the examples you gave are of this kind.

Some examples I know of that have actually been considered to cause some difficulty for analysis:

• French verbs and the prefixed pronouns (especially the non-subject pronouns, but to an extent even the subject pronouns)

• French prepositions before proper nouns (like country names). This is discussed in "The Principle of Phonology-Free Syntax: four apparent counterexamples in French", by Miller, Pullum, & Zwicky (1997) (it's on the page that user6726 linked to; the analysis is as "phrasal inflection" of the first word of the NP).

• English compound nouns of the form adjective + noun that are written closed (like "blackbird") vs English adjective + noun sequences that are written open, but stressed on the first element (like "solar system" and "social worker"). This is discussed in "Adjectives, Compounds, and Words", by Laurie Bauer, which is also the source of these examples.