Just one of each collection.
it varies the higher level you are on the more points between each level
It depends on the mastery percentage of the job.
You can only have a maximum of 501 and many people have that.
joining a clan or family, or by posting to one of the many different sites that are mafia wars add sites. Depending on where you play, you can just type mafia wars into the search site, and many different things should come up.
1 weapon for each member of your mafia with the best offense rating and 1 weapon for each member of your mafia with the best defense rating. The same applies to armor and vehicles. This will ensure you have the highest rating when attacking and defending as possible based on the number of members in your mafia.
so far there is no limit on how many family you can have on your mafia family but you can only take 500 mafia families to attack.
3
320
As high as you can practically go
As of now, there is no known limit.
You should have as many of each item as you have mafia members. This way when they help you out in fights or doing jobs they are guaranteed to have the best items for their level. So if you have 100 mafia members, you should ideally have 100 of each item.
This was a special loot that randomly came up and offered in Mafia wars. Like the gas mask and now they are offering the meat cleaver. The amount of mafia members you have decides how many of these you can get. You can also now get this item by buying a mafia crate.