you can fight all the bosses of New York how many times you may wish as long as you have the requirements specially energy which increases every time you do the job.
There are no levels in NY after Boss in Mafia Wars. This is why they developed Cuba. Now you can keep on playing but...not in New York.
NY> Under boss > Take over and Identity Theft Ring
you get it from a boss fight at level 99 in NY but I'm level 248 and i haven't seen no boss fight with the mayor.
Go back to NY and buy them
Its in NY in the soldier job tier
Go back to NY and from the inventory screen you can buy them
Asian Museum Break-in ..in NY at Soldier tier
NY> Hit man > Assassinate A Political Figure
50 in cuba and 73 in NY so 123
Rob an Electronics Store NY - Enforcer Tier
You need it for some jobs, such as Obtain Compromising Photos in NY
You can buy this with new york dollars under ny store