No, thru is not an English word.
The word 'thru' is an informal spelling of the word 'through'.Example sentence: Read thru Chapter 8
The drive thru was closed at night.
No, you cannot start a sentence with "no" unless you need to do so. No reason exists not to start a sentence with that word, as you can see. No one will care if you do start a sentence with it.
He had so many thoughts going thru his mind
Yes, I can start a sentence with "Is."
Yes, you can start a sentence with a verb.
Yes, you can start a sentence with an acronym.
You can start a sentence with "Also"
You start a sentence with whatever word you need to start it with. A sentence can start with "A" if it needs to. A sentence just needs to make sense.
April may thru August
Yes you can! "For ten long years, I pondered how to start a sentence with 'for'."
can you start a sentence using the word phishing?