understanding the punctuation hierarchy

I have been trawling the internet to get a fundamental understanding of punctuation - more specifically, I have been trying to understand the fundamentals of commas, dashes, colons, semi-colons, and full stops. So far, my understanding is that all these punctuation marks roughly achieve the same objective: they divide sentences in to parts that change the context of these parts to correspond to each other, based on the power of the punctuation mark used to separate the parts. I know that was probably really hard to follow, but bare with me, I have an example that incorporates my understanding of punctuation so far

Bob the farmer has two animals; Gandalf and Jodey. Gandalf the rabbit is such a nuisance: he jumped over Bob the farmer's fence and shed, and ate all his carrots and beans, and dug holes in his front yard and back yard - and went to the farmer's neighbor's house and ate all his potatoes and corn, and dug holes in his front yard and back yard; Jodey the dog can be very naughty at some times, but can be very good at other times: sometimes she likes to chew Bob's furniture and shoes, and scare away cats and children - but at other times she brings in Bob's mail, and barks at intruders.

Question one
In the previous paragraph, I wrote a paragraph that only consists of two sentences: the first sentence, I used as the subject - the second sentence I used as the predicate. Is this the most correct/ effective way to achieve this?

Question two
I use a semi-colon twice in the example. The first time I used it, I used it to "Create an anticipatory 'question' to 'answer'
relationship." I learnt this use for a semi-colon from here http://writingcenter.boisestate.edu/wp-content/uploads/2011/09/Punctuation-Hierarchy.pdf. The second time I use it, I use it to break the second sentence in to two main parts to explain the first sentence, but it does not also "Create an anticipatory 'question' to 'answer'
relationship." Have I got a wrong understanding of how to use a semicolon or can a semi-colon have two completely different uses depending on where it is used?