How much do you-as-DM tend to give, either overall or relative to guidelines? Flip side: how much do you-as-player like to get?
I try to stick to the guidelines of the system. I've been burned in the past trying to fit my aesthetic sense to designers' intentions. (* cough* 3.5e/PF1 * cough*) If the system is flexible, then it's just down to whatever's appropriate for the setting.
How much of your treasure is magic items vs non-magic?
Prefer to err on the side of placing less, but more unique, magic. Again, though, this is tied to setting and system.
How do you "place" it in adventures? By this I mean is it sitting there easy to find, is it hidden, is it always guarded, is your expectation that the PCs will find all of it or miss some, etc.
I don't mind a party missing treasure at all: behind secret doors, in monster gullets, other side of illusory projections, disguised as mundane. And I've got no compunction against placing big, bulky treasure (furniture, piles of commodities, murals, etc) that they can't realistically take. But PCs are rarely hindered by "realistically", lol.
Every group I recall divvied up "the good stuff" basically on the spot, according to whatever makes sense; and the rest was distributed more or less evenly, with the agreement that some fraction was the party fund. So if a character fell into lava, the party fund would melt accordingly.How does your group divide treasure and who decides the method used? Also, how often (if ever) does your group divide treasure?
How easy is it in your game for treasure and-or PC-carried possessions to be destroyed, stolen, or lost? Are your players cool with possession loss and if not, why not?
Personally, I don't mind destroying or losing loot. But ime players generally aren't too keen on that, especially when it comes to favored or especially valuable items. But if you fall in a river full of quippers, yeah, you're probably going to lose a pouch or staff or sword or something. (Of course, the One Ring might find you at some point, too, so there's that.)
Can magic items be bought, sold, or traded; and if not, why not?
Depends on the setting. My personal tastes call for limited opportunities for magic trade (mainly because magic itself is limited). But some settings obviously call for it. And again, IME, players tend to prefer/expect "ye olde magicke shoppe".