Yeah there’s absolutely a rating to look for and N95 is part of that, stateside, you have niosh ratings, you’ll see these wrt industrial ppe, but there are ratings for use with CN and CS gas. My experience with them is the chemical cartridges usually have a p100 filter combined with them for particulate too. Organic Vapour & Acids are easy to get a hold of (Used these when i worked in O&G), I don’t know how well they’d work against teargas unfortunately.
I will 100% recommend north full face, a half mask is probably better than nothing but the full face gives you eye protection too. I didn’t personally like the 3m style masks, but it’s all down to personal preference, just make sure it fits correctly.
My partner does and I have no idea how they stand it, for ebooks, my library works with my kobo so it’s either that or epubs. I can do a tablet for ebooks but I find the phone way too small.
Libby is supported by a bunch of library systems on android, used KOReader for ebooks on android too.