Ive been a commissioned security officer for the State of Texas for about 10 years. When it comes to security posts, the area you work, type of work you do, etc will determine your loadout. Also, check with the company you work for, they may have SOP's as to what gear/weapons you are authorized to use. Last thing you want to do is buy gear that you aren't allowed to use.
Now to answer your question,
There is nothing wrong with the Safariland retention holsters (I use one)
Nothing wrong with a Glock 17 (I carry a Glock 22)
And the armor sounds fine, but forget about the rifle plate..it won't be concealable.
Truth is, the more you wear your gear, it will probably change over the next year or two until you settle on what works best for you. Get all the training you can afford, as often as you can. Oh, and becoming friends with God isn't a bad idea either.
Good luck