First of all I'm sorry but Dragon Lore or Medusa won't fall, most likely of course.
You have the chance to drop three cases and two graffiti / skins per week. But there is a possibility that you can decrease it less than this number. And yes, unfortunately, graffiti generally goes down. Even if you drop the weapon skin, you cannot drop StatTrak and knives / gloves.
This weekly system is renewed every Wednesday at 03:00 (ie 18:00 Central Time). So you have the chance to get drops again.
But with today's Prime account, maybe your chance to drop it is 00.01% (,:

Drops that drop when you level up or rank (how you say).
You also get the chance to drop them on a weekly basis, and these are also renewed at 03:00 on Wednesday. (18:00 as Central Time)
You have a chance to drop the graffiti or weapon skin. In these drops, the StatTrak or knife / glove skin does not come, even if the weapon skin is coming.
-And unfortunately, this is mostly graffiti-If you are really lucky, maybe you can get a $ 5 item.
As I said, all luck :D

You can drop it by watching a Major tournament (such as ELEAUGE, ESL, ..) from GOTV or Twitch (your Steam account must be connected to Twitch). (and yes you don't need to spam! gifts or! boxes in the chat)
Generally, these are souvenir skins and my suggestion is that if you drop them, you sell them without opening them at all, because you usually lose money. (of course you do very well if you make a profit

✦AFK, there are idling servers where you can drop items without eating. You can research and use a few good servers.

✦You cannot get drops while playing with bots or friends (1v1,2v2 etc.).

In order to get a drop, you must stop and not exit from the beginning of the match to the end.

My guide That was it I hope you enjoyed it Don't forget to award it (: