Card collecting questions

[simbol00]

i am lvl 150 now and have a couple of questions about best ways collect cards

• should i always stay at same area to collect like 100-1000 or more cards ?
• or change area after x(like 10-25 or tell me best value) cards collected there?
• should i ignore bosses areas(slower to kill = less cards?)?
• how can i get 250 diamonds every week to keep having x2 (doing expeditions, but it is not enough to keep having x2 every week)
  

and other question about parties

• sometimes some1 joins my party if it full, like we have 3 people and 4th one joints, how can this happen