Sentence structure accuracy and usage.

It’s easy to trim words from sentences – just make sure that when you remove them from a sentence you still get a sentence that makes sense.

The car crashed into the wall and bursting into flames– the accident cost the driver his life.

Is this common usage for the em dash: replacing a conjuction and joining two independent sentences. Can it connect two independent sentences ?

We didn’t know what was happening or where we were going, we just ran. Hand in hand.

Hundreds were not going to do the same that night. Not ever. Is 'not ever' a sentence and hand in hand? Is this accurate usage.

Hundreds of people suffered and endured so much more pain than me; they lost parents, siblings, aunties, uncles, cousins, and friends, saw things that they shouldn’t have and which will traumatise them for life.

This clause in bold: does it require an 'and' before saw?

When using 'though in a sentence what is the difference between.

the dog was sent to the shelter; though,the dogs bark was worst than it's bite.

the dog was sent to the shelter, though, it's bark was worst than it's bite.

When we use a transitional word with bracketing commas versus when we use it with a semi colon.