OK, I will try to ask just one question this time. Let's say I start a new game, and I open every Arcane Chest in the game, can I expect every time (if I start a new game with different name and character) to find at least 1 of every possible Arcane Item just from the Arcane Chests?
Muro! Muro! Muro! Until the Knower of Answers is summoned, I'm gonna wade in with a guess and say no.
No. Each chest is completely random. There are a lot of random chests though and you'll realistically find most every item in the game at some point.
To clarify one should add that not every chest called 'Arcane Chest' is randomized. There are quite a few with fixed items that generally contain unique (often cursed) items. Also, as I'm sure you've noted, there are other containers than 'Arcane Chests' that contain rendomized gear. There is, for example, a box on the crash site called 'Factory Discards' which contains randomized technlogical gear. As everything else that's randomized in Arcanum, the content is somehow based on your name (possibly also your race, gender and/or background) but I haven't seen any answers as for the inner workings of these algorithms. I am however fairly certain that you'll never find tech items in 'Arcane Chests' or magickal items in 'Factory Discards' or similar containers.