Unable to install xcode on mac os

[Jaymin]

Hello,

i have few questions below..


1)i got new macbook pro 15 last week and i want to install xcode 4 or 4.2, when i click on install xcode from appstore it says Xcode assistant can`t be installed on Macintosh HD Because Mac os x 10.6 or later required...how to solve it?

I am using Mac os x 106.8 build 10k546 os which is already installed on mac from the day i bought it.


2)do i need to buy lion os from apple to develop apps for iphone,ipad and install xcode??