Whether this writing is good or bad depends on why it's written and its desired outcome. My understand is, our OP, David, wants an answer to this central question. "May I photograph the exterior of a VA hospital". The expected answer is, "yes," "no," "yes with the following conditions."
The answer doesn't change depending on OP's thought on the subject or what transpired this query. The answer also doesn't change no matter what the guard at the hospital has said or done. Policy is already there and Daivd is simply asking, "what is it?" With that in mind, 90% of the original letter is unnecessary.
On the other hand, if the intention of the letter is to file a complaint against the guard, VA hospital, or policy concerning photographing VA hospital, and engage in open debate with the agent or the agency in question, then the OP's opinion must be fully explained. Then what's written may be appropriate.
If David wants an answer, it must first be read and understood. The current letter is too long and cluttered for that. That's my take on it.