Question Regarding My Grandfather's Stamp Collection

Hi,

I inherited my grandfather's stamp collection (he'd inherited it from his Uncle who started it in the 1880s). My plan is to keep it and continue to build on it. Right now I am just going through it to inventory and organize it, which at this rate may take me the next ten years. I have some questions that I was hoping I could get guidance on.

What do I do with the extra duplicate stamps? My grandfather kept every stamp that came into both his house and his work. This means that there are often more than a hundred duplicate used stamps of each U.S. There are also usually quite a few mint stamps of each stamp. I have been taking a mint and a used stamp of each and putting it in an album but that still leaves a lot of extra stamps. Is there like a standard number I should be keeping and what is the best thing to do with all the others (right now I am just putting them in glassine envelopes with their scott number written on it). I don't really think I need all the extra stamps but I also don't feel like I currently know enough to do anything further. I haven't started sorting through them yet but I know there are also a lot of duplicate German stamps.
While his later collection wasn't very organized he did have some early albums. The earliest stamp album is just an old ledger book with the stamps hinged to it. There are then three albums of postal stationary that are attached to paper using photo corners. Should I remove them from these albums and put them in mounts in the new album or just leave them as is? (I have ordered a ph testing pen but I have my doubts about the acid levels in the paper.)
Regarding the postal stationary, is there a numbering system used for them like the catalog numbers for the stamps? There is also a lot of it that is newer and once again duplicative. For the US post cards from the 70s and 80s there are often about five or six mint versions and 5 or 6 FDC of each. For now I just put them in postcard sleeves in an acid free photo box since that seemed less urgent then the ones that are on paper that may not be acid free.
There are also a lot of stamped and canceled envelopes and postcards (some to him and his family and some to names I don't recognize.) Datewise they span from the span from the 1920 through the 1990s and the envelopes pretty much never include the letters. I went through them and separated out the first day covers and the covers that are otherwise meaningful (i.e. from stamp expos or events, a couple between my great grandparents, postcards between the family that historical family significance, one that was a Gettysburg postcard that had a Lincoln stamp on it that was canceled in Gettysburg on the anniversary of the Gettysburg address) but I am not sure what to do with the rest.

I am sure I will have more questions coming up but these are the one that have come up for now. I will upload photos of the albums so that you can see kind of what the situation with them is.

The Stamp Album (part 1)
















Postal Stationary Album 1





I hadn't realized how long it would take to upload these. I have to be done with this for the night but will try and upload more images tomorrow.