No, it is not proper english. I would try to avoid putting Because at the beginning of a sentence as well. Try This is true because... or The reason for this is...
No, you do not need to put a comma after "To begin with" when it is used as an introductory phrase in a sentence.
I will begin by searing the steak.
The snow will begin to accumulate once the ground freezes.
He was a martyr for his cause, and died believing in it.
Yes you can put emphatic in a sentence . ie : He was emphatic about the outcome of the game.
Example sentence - The alligator and the antelope put their hats on and went shopping for apples at the local grocery store.
The cause of death will be determined by the coroner's inquiry.
An exclamation mark comes at the end of a sentence, and you generally do not begin a new sentence with the word and, so in general you will not have the word and after an exclamation mark.
He will never forsake you or cause you harm.
Frostbite can cause a loss of sensation in the affected part of the body.
Yes. There is no word that cannot begin an English sentence.
Yes, you can begin a sentence with the acronym "NASA."