A SRAM PC-850 should work, as should any 6-7-8 speed chain. If the PC-48 chain was closed with the provided Powerlink you shouldn't need a tool to take it apart, although master link tools like the Park MLP-1 (I have one and like it) make the job easier.

You will need a chain breaker tool to remove links to properly size the new chain. No tool is needed to close the Powerlink.