This verse is interesting because the "your" here is plural while the hair and head are singular. It is as if his audience share a single head.  "Perish" is the final word here, the punchline if you will.

The Greek word translated as "but" is used as the conjunction "and", but it also is used to add emphasis ("also"). In a series, it is best translated as "not only...but also." It is never has the sense of "but", which can be two other Greek words.

There is no "there" in the Greek. It can be added when the verb appears before the subject but that is not the case here. 

The "not" here is both of the Greek negatives used together. Greek has two negatives, one objective, one subjective. The use of both together is more extreme, like saying "you cannot really think."

"Hair" is the Greek word for both the hair of humans and animals.

The Greek preposition translated as "of" means "out of" or "from." In Greek, they use the genitive case instead of a preposition for the types of phrases with usually use with "of." In the other verses with the phrase "hair of your head", the noun is genitive and no preposition is used as it is hear.

The word translated as "your" is plural addressing a group of Jesus's listeners.  It appears after "head". The form has more meanings in Greek than the simple possessive. Because it is plural, the sense is "a part of all of you" since each person has their own hair on their own heads.

The term translated as "head", it means "head" and "top" but also the completion of a thing (as we say, "bringing it to a head"). It is also a metaphor for life. "Losing your head" in Greek doesn't mean an emotional outburst, but being killed.

The word translated as "perish" means to destroy or demolish. The form is not passive but the middle form where the subject acts on itself or for itself.