Question 1-correct
Question 2-totally depends on 2 things; how many inputs you want/need, and are you a guitarist that wants to skip using an amp and mic. The package is nice, but you can buy PT10 software for $300-$400.
An iMac can make a great machine, BUT, make sure it has Thunderbolt. Because they are small and have no room for more internal drives(and Pro Tools is iffy on USB drives with Macs), thunderbolt is your ticket to extra drives. Then, do you want/need firewire? If so, you might shop for a slightly older model(refurbs are a great deal) so you can get both FW and TB.