- What are the stickered guns worth. (buy / sell price)

A lot.
More serisouly, prices are changing a lot, depending on the sticker itself , depends on the team, if the stiker is Holo or not, depend on sticker placement, sticker amount...
It also depends a lot on the price of the item itself without stickers.
Basicly, some small items wich are not even 10 K worth, with non holo stickers would only be overpriced by 5/10 K with non-holo stickers, still depending on placement/amount/team (like, 1 CoL isn't as cool as 4x IBP non holo).
Now items that are quite popular like M4 or AK skins will mostly be more overpriced because they're indeed popular, and also often have a 'basic' price wich is higher (the price of the item itself with no stickers).
Also, the value of the item itself will vary a lot depending on the buyer, like, I love reason stickers, and actually, I won't mind overpaying 1/2 K for an item with a reason sticker just because of it ( I gave 10 K overpay for my AWP for a reason on scope, while the sticker itself is only 18 K).
We can't really make a kind of price list for kato items since there is a lot of parameters such as the item itself, his float, his pattern sometimes, the stickers themselves, holo or not, placement, team etc...

- How does sticker placement impacts on prize

It'll mainly increase prices for items such as AWP where it can be on the scope, or for the AK, when it's on the wood, basicly an item will cost more if the sticker is at the most visible place rather than if it's on the cross of the weapon, out of the field of view of the player.

Since you got a nice angel pattern, would say that you could get 5 K over market max for this.

I think that the max you could expect should be something like 220, but the hole & ring aren't really clean, and even if there is 3 webs, their placement aren't that good so yeah, I can't promise that you'll get 220, you could get that value in items.

you failed to copy paste the link for the screenshot
http://gtm.steamproxy.vip/sharedfiles/filedetails/?id=600328700
this one should works better.
Actually I saw the quite same pattern (here: https://redd.it/40rrhr) for 205 K but it was Factory new and the diamond part was quite bigger.
Since most of the MW kara slaughters are about 140 and since yours doesn't really have a wonderful float either, would say that 150 Keys would be nice, since it's hard to overprice that much a skin while there is the FN version for like 155/160 Keys

People are paying at least 110 Keys for them, you could get more (up to 120 probably) if the float of your knife is really nice.
also be careful of the fact that their is actually "full" and "max" fade according to some people. where "max" is the highest fade (yours is max) while full is the second highest fade.