I'm probably the only poster to this board who would not know what to tell someone about a firearm that he had for sale

I am not a shooter nor am I a knowlegable collector....so I would have to rely on the kindness of stangers if and when I would decide to sell one or more of a gifted/inherited collection....and somehow I can't see even the kindest of buyers offering the fact that I might be selling it too cheaply and offering to pay me double what I was asking!!

Some of you may remember an earlier posting where I attached a pic or two of several of the double rifles in the collection and solicited your advice on how & where to sell them (auction vs consignment vs direct sale)....you also advised that I have a knowledgable individual look them over to offer a better idea as to possible values.
I DID travel with a good portion of the collection ~ mostly rifles ~ and was excited to meet another board member who looked them over and offered his opinion.....we spent an afternoon together in his home as he looked things over and offered an opinion or two, he made some notes that I wish I had thought to ask for copies of....mostly measurements I think....and I am greatful for his hospitality!
Being a firearm novice and having no real interest in shooting I did not pay enough attention even then to all that was said....so here I am again and hence my question ~ what does a prospective buyer need to know?
I know they'd want to know #1 - manufacturer; caliber or gauge; model number (if any); #2 - length of barrels; #3 - LOP (I assume this to be from the front trigger to the end of the stock or pad); #4 - overall condition with notation of any obvious flaws; #5 - sidelock/boxlock (I have NO idea here unless I look at a reference guide); #6 - weight (can I put it on a bathroom scale?); #7 - asking price.....#8 - barrell wall thickness if it's a shotgun (right?...and just HOW does a novice like me determine that!

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OK....please help me out from here!
I know that good pics would be a must and the "how to" for that will have to come in another post.....
What I am hoping to achieve here is a good BASIC list of what a good "For Sale" post needs to include