1) Llamas - I assume you don't know what these are. They're like grounded "air" drops. In the shape of Llama, they'll provide you with ammo, resources, nades and/or health packs.
However, the recent update will cut down resources provided from 500 to 200 as well as removing rocket ammo from the Llama.
2) Mats found within chests or just simply lying around in a house will now drop as stacks of 20.
3) Farming for materials is unchanged.
Honestly, unless you're a pro gamer, you'll struggle a lot and I mean a lot. Firstly, it's third person so nothing like your average COD or Halo. The shooting mechanics are different, the ARs have a tonne of bloom, snipers are not hitscan, shotguns are inconsistent yet the most commonly used weapon. The final hurdle to overcome which may take a while is building. If you don't know how to competently build, you're fecked every time you come up against a semi decent player. I feel for relatively new players as the game has advanced so much since release that it's almost impossible to get used to it quickly.